revhappy said above "i dont know what will happen" but no one here except perhaps those American Honda people combing the boards to check on what's being said.
And they won't tell you.

I can picture the RSX going upscale along with Acura. They could cut it too.
It depends what American Honda management wants Acura to do of course.
They run the show as much as they can given products from Japan as well as whatever manufacturing capacity they have in North America to make vehicles from the Accord and Odyssey platforms (TL and MDX).

If the RSX stays around and goes upscale, I don't see it conflicting too much with the new Si (we need more details on what the new Si will do first, of course).

If the RSX is dropped AND its JDM model line (Integra) is also dropped, then the stage would be set for something new.

I think it would be in Honda, Nissan, and Toyota's interest, once the coupe market regains strength in the US again (fair chance of that happening; I don't see it completely dying off) and also in Japan and other world markets (where Eurotrash hatchback boxes and sedans are more on order) ...

... in their interest to revive the Prelude, Silvia, and Celica nameplates which have historical, performance, and aspirational value for those who don't or can't afford to buy a luxury performance coupe or don't need or want a midsize family coupe. I say that the Celica is totally rooted in some 1970s/1980s or that the Prelude and Silvia are rooted in some 1980s/1990s context is a valid argument but not necessarily true.

In any case, as Honda, Nissan, and Toyota become more US-oriented you will see fewer imports from Japan and hopefully that doesn't mean that sporty import compact coupes are dead. The yen is currently 102-103 to the dollar as of Friday. Yuck.
Does that inspire Nissan to develop a new RWD platform when they already have cut down so that no model really has its own exclusive platform AND their plants are running so lean that a small steel shortage cuts production for a week? Does it inspire Toyota to do anything other than chase the middle-aged middle market with plethoras of Camrys, Highlanders, and Siennas? And Honda seems more focused on making the Civic and Accord even more mainstream (is it possible?) - bigger, faster. Honda's past and also the need for them to have some kind of affordable less-than-total-luxury specialty coupe to maintain street cred means they're in the best position.

So perhaps the 2006 Si is where it all ends, versus whatever model Scion currently runs (the tC now, perhaps something else later because Toyota stated they consider the models to be disposable).

It's not like Mazda, Mitsubishi, and Subaru have enough resources to put together honest coupes. They're focused on convertibles, weirdo rotary-powered pikachus, and rally boxes. Yuck! Mazda is on a tight leash held by Ford, Mitsubishi is falling and intends to spruce up the Lancer/Galant further (limited Ralliart trims) and Subaru I think has issues with pressures from GM, new design directions, and a deer-in-the-headlights boardroom situation with the Impreza. What to do with it? It's fairly successful right now. If they make it bigger, it's not much different than the Legacy.

Is this mike still on? oops.