Yes, I know the hypothetical. However, I'm talking about reality. If YCombinator is an option, I'm going to take it.
1) I'm leaving my desktop app available so my current customers, 93% of whom of 153 survey respondents say they love it, can access it. I already know I can deliver software that makes people happy enough to pay money for it. I'm just creating a free version and getting it up to distributors to see if it can make even more people happy than I can imagine.
2) Finding cofounders on News.YC for a web-based app the team agrees on.
3) Applying to YCombinator.
4) Working as long as it takes to make a lot of users happy.
PG, Max Levchin, and other investors favor teams who are dedicated and flexible versus one specific idea.