If a President with major change ideas is elected now, they will get nothing done, so in this cycle it doesn't really matter anyway. Your 180 degrees becomes 90 degrees of change and 20 becomes only 10 is a flawed theory - this is more of a sellers market and negotiations are terribly one-sided ;)
I'm also not so partisan that I think being a Republican (or a Conservative up here) is a bad thing - certainly this latest version of the Republican party toadies for Trump are revolting but my guess is a lot of them will pay a political price for this.
There is not enough overall support for a progressive revolution so it is a recipe for more gridlock... there's a five alarm fire that needs to be put out first before any sweeping changes can be made... the nominee just needs to have the means to put out the fire. However, I'm not averse to any candidate, whoever the Democratic electorate agrees on would have my full support and vote (if I could vote) - a winning fence post might do for the next four years. For now, I think the guy with those means is Bloomberg... all politicians have a past, so I'm not going there. The only one I really don't care for is on the other side (and maybe Tulsi lol).