With no LMB there to eat the fast growing Tilapia, you can expect lots of big Tilapia at the end of the season.

Snakebite, Tilapia can be pellet hogs, but I doubt they harmed the BG growth. BG will just eat the Tilapia. I also can't imagine any scenario where one season of tilapia use could create a situation taking more than 1 year to correct....I also do not suggest stocking Tilapia with only bluegill....TP grow too fast for the BG to eat enough.