There is never going to be a tax plan passed that will benefit the middle class. Some way, any way and every way they can the rich will force a carve out or find an accounting rule to avoid taxes. They will because they can. Romney's 47% will continue and gain in entitlements because they can? Politician will structure tax plans that help them escape taxes and garner them votes.
So all the tax plans being touted right now by Trump, Bush, Rubio are all bluster because not one of them as president will get a plan passed. They won't because Congress is too divided both between parties and within their respective party and in my view GOP has the bigger intra-party ideological gap. Then you have to factor in the FED which in my view should all but disappear from the American landscape
I discount just about every promise a candidate makes. its all bluster.
Beside, time is a major dynamic and has a way of radically changing the political landscape.
Political candidates promises are all about well (Seinfeld's nothing)