It wouldn't be an _impossible_ task to outcompete BCC I suspect, especially if the new owner just lets it coast and wind down instead of staying on top of the game (which Patrick readily admits he hasn't done for some time), but I suspect you'd probably need a PPC budget of around the same magnitude that the new owner just paid to kick-start a competitor - even if you already had production-ready code and a suitable hosting platform ready-to-go.
I think you're right - in that assuming "it'll be paid off in three years" is a naive view of the way SaaS businesses age - but I also suspect there are already several "exactly the same product"s out there already, none of which have got the traction BCC has, and that the value here is not in a bunch of code that makes PDFs from lists, but in the business backend and the historical web presence and SEO.