it would be easier for them by making a reward program where mp sends coins to any coinbase (miner-address) which does not advertise it'll make bigger blocks.
thats the best way i can imagine to prevent a fork - not that i want them to do that...
Loss of faith in Bitcoin would make make the bribes less and less due to the law of diminishing returns until it lost it's network effect. Really they have no chance and it will be amusing to see just how desperate they become to use this FUD tactic. Their next tactic will be to promote what they consider a superior altcoin. Watch MPs Trilemma blog for this in the near future.