You've basically asked and answered the question regarding Bloomberg
I think he'll outperform Perot, but Perot took votes almost exclusively from Bush H, allowing slick willy to smile his way into the White House. I don't think it'll be quite so clear cut a partisan division for Bloomberg, but I suspect he'll do Hillary more damage than the Republican. That's why I wouldn't want evens about Hillary until we know what Bloomberg is planning to do. He might not beat her, but he might allow someone else to do so.
There's a number of key states where we only need that damage to be 5% (principally Ohio and Pennsylvania) for the Republican to suddenly be winning the White House
What if the candidate is Trump though? It's another factor why I think I'd quite like to take a long term bet on Trumps majority as a value proposition. He could win a landslide with something like 45% yet, which is well within his compass
The other thing that would be decisive is a terrorist incident committed by someone who arrived in the US after November 2015. That would seal the deal for him