How many companies have there been this gen that have been (in total) profitable ?
Probably more than you think.
This will inevitably lead to less diversity (regarding "traditional retail" games)
#1 traditional retail is going out the window soon anyway with digital.
#2 You're only half right about the less diversity. It will lead to less diversity in big budget mainstream heavily marketed games. You can see that happening already. There's 1st person shooters and a bunch of relatively safe, focus tested stuff that comprises those. And it will stay that way and rightfully so. Bigger budget = higher risk and those things are less of a risk.
But it will lead to more diversity with the switch to digital and tons of smaller indie companies not having to spend money getting into retailers, printing discs, etc. They'll have their XBLA and PSN to market their games, and it will be the ones that stand out the most, the most unique experiences, that will be the breakthroughs.
So less diversity on the high end, more diversity overall though.
It will be like modern Hollywood. Only a few big time publishers and a ton of indies trying to hit the big time. And really, isn't video gaming already like that now?
and even those that are regarded as successful may get into trouble.
Of course. Sure there's a lot of companies closing now, but seriously step back and take at look at the ones closing. For the most part their output has been shit for a long period of time or they've grossly mismanaged things like having a huge budget on a game that flops, or distributing their game wrong etc. Sure let's have compassion for people who've lost their jobs, but let's be realistic and take note that if the companies didn't fuck up in one way or another those people would still have their jobs. That's this gen, next gen, all previous gens, and all time everywhere in every facet of business since forever.