There is the rootstock sidechain which is already using bitcoin merge mining and pays btc miners to secure the sidechain and provides additional revenue to miners. Has been up running for 5 years with no downtime and no miner has managed to get 51% majority of the coins.
But rootstock has a federated model and requires trusting the rootstock custodians with the keys to your coins.
Drivechain is an upgrade to this by allowing for trustless side chains where you have self-custodial of your own coins. Being able to have a Monero type sidechain or Eth type sidechain means you could trustlessly use your bitcoin privately and be able to trustlessly do bitcoin Defi without having to trust any custodians while all the tx fees go to miners to secure the chain. The additional revenue the miners receive will also help with the security budget later on as btc block reward keeps on halving in the future.
It would be the last change required to btc. As if anyone wanted to experiment a change they could do it on a sidechain, it’s up for bitcoin users if they wish to support a sidechain, its free market competition basically.
So I am pretty convinced drive chains would be a huge boost to bitcoin. Imo

