Escrow can only be said to solve 100% if the team don't have the power to change the contract address so easily (i.e from the alts campaign point of view) but in a situation where the team decided to change the contract address immediately the campaign is over then what good would be the escrowed tokens? evidently, there is no 100% way of dealing with campaigns that has to do with tokens of the said project because it can go either ways, sometimes when the project refuse or could not make it to the exchange as a result of one thing or another, still the token reward will becomes useless to hunters,  perhaps you narrow your response to the btc paying campaigns and not extend to alts campaigns because those hardly use any escrow.