I don't know if any new combos are really worth the marginal increase in BV he would receive. If he can skate his GPF layouts cleanly it's likely only Hanyu can beat that, assuming he still has 4Lo.
I think 4T3T3Lo is just for practice. But it is interesting to watch Nathan working on 3Lo combo.
In the short term, that is the case, but it's always good to be developing and growing. One thing that Hanyu was working towards was getting rid of any doubles in his combinations. I suppose since his -3Lo combinations weren't good enough, and because he didn't want to have two -3Toe combinations, Hanyu decided to add a -3A sequence, even knowing that he would lose a lot of the base value in a sequence. Also, because a -3A sequence is really cool. If Nathan can ever successfully add a -3Lo combo, he wouldn't need to repeat a 3Toe, allowing him to repeat a more valuable triple, like a 3L or 3A. If Nathan wants to stay on top until Beijing, having additional combos at the ready is always a good thing to do.
Of course, being clean is definitely important, and Nathan did say in a q&a that he wants to add a 4T-Eu-3Sal back in, but it hasn't been very consistent. I also doubt a -3Lo would be very consistent, considering how edge jumps aren't his favorite... but I'm still crossing my fingers that one day Nathan can figure out how to do a -4Toe combination one day.
But, most importantly, stay healthy Nathan! We'd love to see you do new things, but don't break anything in the process!!!