It doesn't alter Sri Lanka's chances or fortunes at 20/20. Murali is pretty poor when it comes to batting and someone like Lokuaraatchchi who will replace him is a damn good slogger in the limited versions of the game and a very good Bat even in FC Cricket.
I don't think Murali's bowling would make a huge difference in 20/20 . That's just my personal opinion.
Murali is needed for SL tour of Australia which is IMHO the No.1 priority ATM.And everything else is insignificant. Thats my personal opinion.