And those people would be spending a lot more money for less.
My steam console would be upgradable .. With free online.
Only thing you would lose is console exclusive but you would gain new exclusives.
You're not going to change people's minds about their priorities when it comes to system purchases unless it's a very compelling advantage you're offering.
The proper answer again, is simply to own everything that has games you want to play on it. No sacrifices need to be made, it's not this or that, it's this and that. However if "that" offers exactly the same stuff "this" does, which you already own, I'm not sure free online or upgradable are the biggest selling points, especially over the games themselves (first party exclusives), or losing out on free games from having the online subscription, etc.
I also don't see why you'd pit it solely against consoles, as opposed to in addition to consoles instead of a PC, that seems more likely to me, but both situations are still about compromising when gaming should be about just having all the systems that have games you are interested in, not picking one.
Sounds like they are to me. I don't see why not.
Especially given that they say this on the page linked in the OP:
Downloadable soon. Free forever!
SteamOS will be available soon as a free download for users and as a freely licensable operating system for manufacturers. Stay tuned in the coming days for more information.