Here's the field as I see it, though i put the caveat that I am not sure the official status of these skaters.
The likely 2019 U.S. Nationals Podium (remember it's 1-4 here)
1.) Nathan Chen. Honestly, the question isn't whether he can stay US No. 1 -- it's whether he maintain World No. 1. I think he's far and above U.S. No. 1 and even if he isn't a full blast, I don't see him letting go of top dog status with USFS. The World competition is highly reduced -- his biggest competition will be Yuzuru and Shoma, with Mikhail and Boyang as the dark horses. He's beaten pretty much everyone at this point.
I actually thing places 2-4 is a bit more fluid then some people think.
2.) Vincent Zhou. I do think Vincent is in the best contention for U.S. No. 2. He finished in the top six at the Olympics against a deep field. He obviously has a lot of quads, but he does underrotate them, as we've seen in various competitions this year. His PCS scores remain relatively low compared to the top men, though I think his efforts to improve with his performance/artistry/basis will likely pay off with a boost in his PCS scores (even if they don't get to the top echelon). For me, Vincent is very focused, but at times, he can almost want it too much and sometimes it does backfire on him. In a sense, he's been most successful when people didn't expect a lot from him or when he's coming off a so-so/poor part of the season. The question is whether he can show he's a top contender on a consistent basis. That remains to be seen, which is why I wouldn't put him as a LOCK for No. 2.
3.) Jason Brown. There are all sorts of questions regarding Jason. I do think Jason had a crisis of confidence this season that lead to him not making the Olympic team and finishing a dismal sixth place, his lowest placement in five years. He's also dealt with major/minor injuries in the last few years (including now with his recent ankle injury) which I believe impacted any momentum as far as mastering quads and maintaining consistency on his triple axel. And yeah, who's going to coach him?
All that said, I think if the stars align, Jason could sneak back into that No. 2 position. The judges continue to score him well and the scoring changes may work in his favor. I also think one thing people are likely underestimating is his ability to improve elsewhere while he's working on jumps. His basic skating skills have improved over the last four years and I think that work will continue to pay off.
4.) Alexei Krasnozhon. I think he too can easily be USA No. 2. He started out very strongly last season, winning JGPF. He had a so-so nationals (due to being sick during the free skate) and then suffered injury during his FS at Junior Worlds, forcing him to drop out. However, this kid had the best and consistent 3A among all the U.S. men and I think he's close on getting a good quad. He does need to work more on the non-jump items, especially spins, and basically I think he's going to need to out TES the field to move up. However, his growing confidence has been fun to watch and he's hungry to improve, just like Vincent.
The dark horses
5.) Ross Miner. I'm not sure if he's going to officially continue. Yes, it's feels odd putting him as a dark horse since he skated so well at his last competition. But the lack of data points make it tough to know whether his Nationals performances were a complete fluke among a seas of lackluster performances. Ross does have amazing SS -- the best in the field, arguably -- and he has landed a few quads internationally. It's not out of the question for him to defend his silver medal next year. But it's also not out of the question for him to end up much lower.
6.) Grant Hochstein (if he continues). He's not officially retired (though he and others have made comments hinting he has/will retire). However since we don't know for sure, I'd like to include him. He had a surprisingly great SP at nationals, but then so-so performances after that. However, he's been on the podium before and I think he can sneak in if the top 4 above do poorly.
7.) Tim Dolensky. Tim has some beautiful skating and great spins. He's been inconsistent on the jumps, which is why he continues to finish 7th in the last three years. However, I think he can continue to improve and could find himself up a few spots.
8.) Alexander Johnson. There's so much to love about Alex's skating. He is an engaging performer and he tends to pick interesting programs. He's finished as high as 6th. It's hard to say whether he has the time (he is studying full time) to master the quads or even get the 3A consistent enough for him to move up the ranks after a few years in the 6th to 8th range.
9.) Camden Pulkinen. He is the JGPF silver medalist and helped the U.S men retain 3 spots at Jr. Worlds after Alexei was forced to W/D. He also has a great 3A and a great performance/skating quality, but we'll see whether he can integrate a quad during this upcoming season. I can see him sneaking in the top 5 or 6 quite easily.
Who can break into the top 10?
10.) Andrew Torgashev. Andrew moved to Colorado Springs full-time to be coached by Christy Krall after a tough season. Krall has been known to get her students up to shape with jumps (she played a big role in getting Patrick Chan to master his quad toe, for instance). Andrew already has high-quality skating and is an engaging performer.
11.) Tomoki Hiwatashi. Tomoki continues to go up-and-down. He can struggle at one moment and then dazzle in the next, as we saw at U.S. Nationals alone. His struggles in the SP left him in 15th but then he did a dazzling 7th FS to move up to 12th, an improvement from his 2017 placement. And let's not forget that he's a past junior world medalist.
12.) Jimmy Ma. The viral sensation! But Jimmy has improved greatly since moving to the Cains in the Texas last season. He finished just outside the top 10, in 11th, beating both Andrew and Tomoki. I'd like to see him get some consistency in the summer, get in the ISP and build some credibility internationally.
13.) Jordan Moeller. He was 10th in 2017 but then dropped to 15th after a dismal SP that left him 20th (though he moved up a few places after a solid effort in the FS). Jordan's had some major ups-and-downs and isn't the most consistent. However he has been showing some progress on a 4S and he has always been a very engaging performer, so I'm hoping he can sneak his way up to the top 10.
14.) Sean Rabbit. Sean's also been in the top 10. But given his lack of consistency on the 3A (he only landed it, IIRC, a handful of times), he'll likely need some help from others.
15.) Emmanuel Savary. He recently switched coaches and is now being coached with Tom Z. He show some promise in the past but has struggled with consistency. It will be interesting to see whether this new coaching home will help him. He is a great performer -- I loved his SP at U.S. nationals this year.