I don't think it'll outsell any current console. Not even the anemic and dying Xbox Series X.
I think that appropriately priced and supported, it will put Valve in a strategic position to actually compete in subsequent console generations as a real player. It's a little behind in terms of specs, but with as slow as uptake of this generation has been, I expect that developers will continue to target base PS5 specs for another six years at least (PS6 supposedly landing in 2027). Then they can drop their Steam Machine 2 in 2029 or 2030, hitting base PS6 specs at an affordable price. It's been a winning approach for Nintendo.
It's not useless by any definition, but will it really outsell the PS5? Because that is, to me, what the headline is implying...