I think it's unlikely it sits empty for 10+ more years, but I'd still take that over Play! -- because if Play! was actually built and opened, we'd almost certainly be stuck with it for much longer than 10 years and the whole concept was a ridiculous waste of space for an EPCOT pavilion.
If there was some kind of guarantee that Play! was only going to be around for a few years instead of being left to rot for decades (like, say, Imagination...), then sure, it'd be better than nothing. Since that was very unlikely, it's essentially opportunity cost, both of the use of the pavilion itself and of the funds that were going to be spent on Play! potentially being allocated to something better (yeah, that seems unlikely too).