Apparently hit some snags. I would guess part of it is the skyrocketing cases in the US with no end in sight. I assume the plan was always to have them in Canada if possible, for many reasons (a big one is how much cheaper it is for them to do it in Canada) but like you said it seemed unlikely until recently - but that was primarily because of the border closures and quarantine issues. Apparently Vancouver also hit snags and was eliminated as a choice along with Vegas.
My guess is they had already chosen EDM and TOR *if possible* and were going to go to Vegas and wherever only if they had to, so they were waiting for the absolute last moment possible.
As for NHL players being infected, we have to remember we aren't even in camps yet so at this point there IS no bubble. So cases are kind of irrelevant because nobody is restricted. Now, if they see cases once the bubble is up then THAT will be something to be concerned about, though let's be honest the chances of ZERO infections are pretty slim.