Sanders would've been a weaker candidate than Hillary after he was attacked; also, Bloomberg would've ran, and picked up most of the wealthy white East Coast liberals (places like Manhattan and NoVa would've rebelled against Sanders), along probably with attracting the Mormon vote by process of elimination. He would've focused on buttressing a few key states Sanders would've run stronger with Midwestern whites, and probably no weaker among blacks or Hispanics when all was said and done. It's hard to know just how well he might've done on the East Coast, though.
Trump has 231 EVs; Sanders 218; Bloomberg 6, with 83 being three-way races that are difficult to predict. These states all rejected Sanders by large margins and have decent numbers of urban white liberals who would be very averse to him; if Bloomberg carpets the networks with negative advertising, he could conceivably carry them all. Or the natural lean of the area could see Sanders winning these states anyway. A few of them have high Republican floors, especially DE/NJ, and with the correct vote splits could see Trump winning their EVs (the sort of East Coast suburbanites in places like Montgomery County and Westchester County who normally vote D but occasionally vote for the correct R would desert Sanders for Bloomberg en masse).
So, yeah, the election probably goes to the House. Sanders might still win it narrowly (NY/PA/MD is enough, and he really
should carry them all), but it certainly wouldn't be easier than Hillary's defeat of Trump.
