Sorry mate, you totally screwed up, you should have put all your resources into Machamp.
Seriously, the question is really how much use will you get from your 98% Blaziken (I assume it's either double Fight or double Fire) between now and the time Mega Blaziken comes out. Worst case you can always TM it to double fight moves. It's also possible that you have to take the final form (Blaziken) and do something to it to get the Mega form, so it won't be a waste at all.
I wouldn't worry about it. Use it in good health against Regice and Registeel. (Ironically, against Regice, the C/OH Blaziken is strongest rated Blaziken on Pokebattler.)