This chip is just too soon to SteamDeck 2. There is no point to make a SteamDeck 2 while they haven't fulfilled the preorders if the 1st model.
It wouldn't be too unusual for Valve if they fast-tracked development and pushed straight for SD2 if it turned out convenient for them; after all, reservations combined with manufacturing delays were far outpacing their capability to meet all of them and they've been doing some minor beta-testing of alternate parts (mostly alternate fans and supposedly memory chips in order to ramp up production). It would also be similar to some Kickstarter/Indiegogo fundraisers, where later reserve holders got a free upgrade to an updated version after early mass-production defects were discovered and corrected, or original parts could not be attained further, thus alternate or upgraded parts were substituted instead while offering exchange or heavily discounted coupons to the extra early adopters.
In this case, early adopters got their units first, and could theoretically be given a discount towards the SD2, while those still in line could be given the option for a free upgrade to the SD2 version of their reservation; price locking it for them at the cost of the old one. All in exchange for giving up one's place in line to head back, but one of the first in line for the SD2 version of their original choice (Basic, Middle, and Top-end) at a much cheaper cost.
Now I'm not saying it will happen either, but after following some development/refinement on the fly from various successful fundraisers, it's one option Valve could do. Their main goal is to get SteamDecks into as many hands as possible, further helping to cement control over the game libraries since most will not attempt to hack Windows onto it, and instead just use Steam OS and buy whatever is on Steam that they enjoy. It's about getting even more people into their ecosystem and buying into it. So if financials look better for them to just move on to SD2 because the parts are ready, they could do so. Moreso as they're not as beholden to game studios as the legacy console makers; who use more proprietary hardware elements than the SteamDeck and have to give them more time to fully optimize for each console.