GLP-1s aren’t “forever drugs.” They’re eliminated so fast from your system you need to keep taking them to keep the effect. That’s the opposite of a forever drug. If you go off them, you just return to the way you were.
maybe i could see something based on modified gut bacteria that produce GLP-1 drugs inside your body. that would run into problems with dose regulation but at least you can flush them out with antibiotics if you get a bad response.
In any case, we just don't know what kind of long-term effects these drugs have. No one knows what happens if you come out of them 30 years after you started.