Conrad Black thinks Michael Bloomberg doesn't have a chance of winning the presidency:

It is possible that, with a still-overpopulated field, Mr. Bloomberg could get some traction as obviously the most accomplished of the Democratic contestants. However, I don't think any of it will work. His strategy — accepting no outside contributions and paying everything himself while his company news service blasts Mr. Trump without commenting on Mr. Bloomberg — will backfire.

Avoiding the first four primaries will stir up great resentment; the DNC won't change its debate-eligibility yardstick to accommodate him, and I doubt if Mr. Bloomberg will get much response. He isn't an electrifying figure; he never should have recanted on stop-and-frisk (it worked); and the country doesn't like the idea of buying national office.

Photo credit: Gage Skidmore.

But if Bloomberg swings and misses for the nomination, it won't stop him from spending hundreds of millions to defeat Trump next November.  Even though the country is very polarized with relatively few switchable voters, the turnout percentages matter; will people vote on both sides in roughly equal numbers?  Trump would benefit from more blacks voting for him (he won 8% last time) or not voting at all (black turnout was down in the Midwestern states Trump won that Obama had carried).  Trump will not win 34% of the black vote (a number in two recent approval surveys), but he does not have to come anywhere near this number to still benefit from a shift from 2016. 

Bloomberg ran very effective ads, in high volumes, targeting a dozen or so Republican House members in 2018, and his late ad campaigns took down an Oklahoma Republican who was coasting to victory (or so everyone thought) and probably assisted Dems winning other races who were known to be competitive.  Hillary had a billion-plus dollars but had a chaotic campaign.  Bloomberg is far more systematic.