I mean, I don't have any direct sources on hand to refute that, but that logic doesn't pass the sniff test, at least to me.
The Deck is an incredibly successful product that constantly sits near the top of the "all sales" chart, is incredibly important for Valve to keep computing open (and not lose their entire business model to Windows' enshittification), and has virtually 0 overlap with any of the products coming out.
If anything, I'd expect them to cancel the GabeCube before the Deck, at least until the Deck has a successor.