This stuff seems to work incredibly well on Steam - I don't see why it wouldn't help here. The big value isn't just the front-page promotion, it's also the time limited sale for a bargain price.

I suspect the main effect in the long term will be to boost the app's ranking in its category (because of how many downloads it got) and in search results (based on downloads, active users, ratings, or whatever algorithms Google actually uses). Whether the app will manage to take advantage of that and hang in there, or will fade back to obscurity, will probably vary from app to app.