The game itself might tank, but if WOTC plays it smart and comes out with a new batch every 3-4 months - I think they will still sell a lot of these minis for regular D&D.
Pre-painted minis at $1.25 are a good deal - and the paint jobs are as good as or better than any other mass-produced pre-painted minis I've seen (maybe I haven't seen them all).
I like painting minis but I also like having minis ready for whatever I am throwing at the party - and my painting schedule can't always keep pace.
Right now, my only complaint is that the first round has a few creatures that don't really see much action in most games (tieflings? - a hobgoblin would have been a better choice for the first batch, save those extraplaner beings for a later release, IMO).
But I am happy with the first four boxes I got. All the FLGS,s around here have already sold out - so I think the demand is there.
Heck, I know the randomness puts off some people - but the sales figures are pretty good right now, so like it or not these little guys are going to persevere for a while (I predict).