Random post here, but if PLvsAA does hop the pond, I'm very curious as to how they'll market it. In Japan, the advertising for the Layton games tends to feature the storyline pretty heavily, so the PLvsAA spots also devoted a good amount of time to shots of the animation and the like. In addition, AA is bigger in Japan than it is in America by a pretty sizeable chunk, so images of Layton and Phoenix sharing pointer finger duty were well received.
(That said, it's worth noting that PLvsAA seems to have underperformed in Japan - it did about 128,000 copies its first week, less than all other Layton and AA games save Miracle Mask. Of course, there are digital sales these days, but I doubt that made a huge difference. It's telling that one of the free, no-fourth-wall DLC episodes (which are clearly already on the cart) makes a reference to the number of people who've played PLvsAA, and it's much higher than 128,000 - I think Level-5 was a little optimistic on the sales numbers.)
In America, though, Layton games are still marketed first and foremost as puzzle games, it seems. Ace Attorney is moderately known, but not anywhere near the level the Layton games are. How are they going to push it - as a crossover, or as a 'special' Layton title?
Even the name could be a spot of trouble. Keep it as "Professor Layton vs. Ace Attorney" (which honestly I figure they will) and they might get casual Layton fans asking, "what's this Ace Attorney thing? Why is it a VS game? What sort of weird crossover is this?" And the other possible obvious change - "Professor Layton and the Ace Attorney" - doesn't really have the same magic to it as, say, "Miracle Mask."