I am agree with your opinion, between BNB and ETH prices increasing as the year goes by, it will result in expensive gas fees for the BSC and ERC20 blockchain, and I think people will migrate to Polygon, causing Matic prices to rise significantly, just my humble opinion.
And when everything increases gradually in each year, then the effect on the transaction Gas fees will also be the same because it is a very real thing for every coin that already has its own blockchain such as ETH, BNB and also Matic