I don't think Microsoft will leave a void even if they bow out. They'll just sell their game hardware business to someone else. After this generation's silliness I'm sure it could be purchased for a steal (a really expensive but relative steal).
A steam box would be ideal but now that the consoles are moving to x86 they basically are steam boxes. The only benefit of a steam box is having the freedom of a pc with standard hardware for developers to develop for. I think that consoles may have a lot stronger foothold than pc fans would like to think. Especially if the console companies like Sony continue to produce such strong first party exclusive support.
A steam box would be ideal but now that the consoles are moving to x86 they basically are steam boxes. The only benefit of a steam box is having the freedom of a pc with standard hardware for developers to develop for. I think that consoles may have a lot stronger foothold than pc fans would like to think. Especially if the console companies like Sony continue to produce such strong first party exclusive support.