2k DEC for a Wild Season Permit will make many players who don't even earn that much stop playing. As a result, they will stop renting SPS and cards, causing the price of cards and SPS to drop. Since many use bots, they probably won't switch to Modern.

The correct approach would be, for example:
Wild Season Bronze Permit: 100 DEC
Wild Season Silver Permit: 250 DEC
Wild Season Gold Permit: 600 DEC
...

And slightly increase the fee for renting cards and SPS. Use the revenue collected from the Season Permits and the extra fee to fund the reward pool for the Wild format. Take the amount that was for the Wild format pool and double the reward pool for the Modern league or not.