5 looks to be the best case scenario, especially with reference to the seemingly middling and divisive reception of S3.
Part of me wishes 3 could have been released during the 6th gen, seeing as Yu has stressed that the plot of this game was to be inward (Ryo/Shenhua), not outward (the plot many, myself included, desired). So to speak, he could've gotten that part 'out of the way', and we could've picked up with a game more focused on the outer elements.
The team really needed to make this installment appeal to the masses for sales, but in the timing of the plot, this was a damned if you do/don't situation. Either you skimp the crucial character development or the more "external" aspects of the series (NPCs, plot, etc.) or you skimp on the integrity of his vision (as if we'd expect that).
I'd really like to see 4, but the internet mob seems to grow angrier/negative each year, and I don't just mean gaming. It does seem that detractors are more so bored than hostile, but I truly can't imagine another kickstarter going down well.
My honest answer? I'd like to see them attempt 4 but, if it flops and prevents a 5, please do release the rest of the story in print or something. I've never understood that notion of "if he can't make it his way, just let it die with him." You don't have to read it if you don't want to, but some of us care enough about the story that imperfection is better than giving up (I'd think Ryo would agree, no? Go down fighting.)