Really dropped the ball here Gamefreak. Our favorite fire dragon really would've liked being a Fire/Dragon.
I'd like to point out Charizard wouldn't have really benefited from a type change because its main drawback is its typing's weakness to stealth rock.
Because mega evolutions don't activate until you attack by the time it got out on the battle field it would have lost 50% of the HP... And GF seems to want to combat dragon attack spam
Rather than a new typing what Megazard needs is a massive boost in at least speed and special attack. With speed needing the bigger boost so it can compete in the speed war (I'd say at least 130 which would help it match unboosted 130's)