Also, this change would directly influence how many players will be able to play in Wild.
I see this mostly as a zero-sum setup, where most of the SPS rewards that are earned in Wild will be burnt as the seasonal fee.

With 20k $ SPS rewards distributed each season in Wild, with current DEC prices, this would only result in roughly 13k players for the Wild format (if the SPS rewards were distributed evenly).
If DEC were at peg, only 10k players.

With better accounts earning more than the weaker accounts, the actual number of players that could be supported by these rewards is even lower.

What this will lead to:

1. With only 13k players in Wild format, the value of current Wild cards would be destroyed. The incentive to rent cards would be completely lost. Most accounts will probably earn more or less what they spend that season. Why would they spend money on rentals if that would not pay off? Lower rentals probably will lead to lower card prices.
2. With only 13k players in Wild, the price effect for sets rotating out of Modern would be even more drastic. With that low player count, there would be nearly no demand (owning or rentals) for sets that rotate out of Modern. Let's assume we get a lot more new players. The Wild format with its rewards can only support 13k players. So new players have to play in Modern (which is a good thing), for that they buy packs which they can use until the set rotates out. But if Modern has a higher player count than Wild and therefore more cards than ever will be needed in Wild, the card price will eventually go near burn.

Of course, we have Land for older cards. But with Chaos Legion cards setting the floor of PP/$, any new set that eventually rotates to Wild would probably go near the same prices (because there is no real other demand anymore).

So while this fix would probably help short-term, I see really big problems in the future. I mean, who wants to buy packs if they know that after two years they go to nearly zero?
Of course, this is a bit exaggerated, but overall I see this as really problematic.

I would really prefer one of the options above.

So overall, I'm pretty sure this change would hurt the price of all current Wild cards drastically and will make the price decline of sets rotating out of Modern even more drastic.