I honestly wouldn’t count on it. They are manufacturing one SoC for 5 product lines at this point - and remember, the RAM on M1 is built into the SoC. So I don’t think you can read this much into the decision to put 16GB on the top end iPad Pro. In my opinion it could easily come down to supply chain quirks and “why not?” decision making.
In other words, if they weren’t *already* mass manufacturing 16GB M1 SoCs, would Apple have engineered 16GB option into iPad Pro? Probably not.
They could've just as easily used M1+8GB across the board and not made any mention of how much RAM is installed. That was their modus operandi on all iPads that have been released before.