Many of the American and Canadian summer events have an international flavor to them. They usually attract competitors from several countries. The ISU wouldn't have to work to make them international; they already are.
The question is, what characteristics would the competitions have to have in order to qualify as official international competitions that count for skaters to earn official minimum scores that qualify them to skate at ISU senior championships? And that might also count toward ISU world standings?
According to Mathman's post #2 in this thread,
In order to qualify for this designation the event must have a total of at least 8 ladies, 8 men, 6 dance couples and 5 pairs. Each discipline must have skaters from at least four different countries (three in pairs), I don’t see any requirements for the judges, but the three people on the tech panel must be from three different counties.
So the minimum changes that would need to be made would be making sure that the tech panels for the senior events include members from three different countries.
Then, for any events that have enough entries and enough different countries represented, that event would meet the requirements mentioned above.
But other considerations might arise.
Do the judges need to have international judging appointments recognized by the ISU, even if there are no restrictions on which countries they represent? That would also affect the way panels could be staffed at these events. Remember, these events as they currently exist are club competitions, albeit prestigious ones, and many of the judges on the panels are not international or even national judges.
I'm sure if the event were designated as an official international, it would become even more popular with skaters and there would be no trouble getting enough entries. If anything, the problem might be too many entries.
A) Is there a maximum number of competitors from the host country (or any other single country)?
B) Do the skaters need to be assigned to the competition by their federations?
or C) Is anyone with the appropriate test credentials free to enter the competition, like any other club competition, just by filling out an application form and paying an entry fee?
If A and B, then the majority of skaters who currently participate in these events would no longer be able to participate. Turning an existing event into an international would take away an opportunity that is valuable to many skaters and to the clubs that host the competitions.
If C, then any US skater who has passed the necessary tests (junior tests, since most of these club competitions allow skaters to "skate up" one level), and any foreign skater who has passed the US tests or otherwise qualifies to enter a US competition at senior level can buy her way into an international. Ditto for Canadian events. In that case, expect the ladies' field to be unmanageably large and to include skaters who don't have the skills to qualify for US or Canadian Nationals, much less to do well enough there to get international assignments.
The events could not continue to exist in their current form and also serve the senior B function. Something would have to change.
Since the current events already serve valuable purposes that should not be thrown out, I think it would make more sense to add a new event, not to take over an existing event and throw out some of its current valuable functions.