GGG is impregnable at 160. Most of us have already concluded that. Age is really his only opponent worth mentioning.
Hopefully he makes all these fights happen, Golovkin is only getting older so the clock is ticking and his athleticism will only decline. The good thing is he has a superb boxing acumen, extremely technical and has heavier hands than Colossus, his jaw is forged from the finest steel the Soviet Union could muster. With these attributes in mind I could see him have a long successful career like Hopkins did, his boxing IQ, chin and heavy hands are the key to his longevity when his athleticism declines.
The only fight that could genuinely be made and would be a test is De Gale. If GGG survives to half way he wins but with DG's odd angles and movement it would be a tremendous encounter.
I think Charlo can give GGG problems in exactly 2 years. If charlo waits just enough when GGG slowly down then I think he has a chance
Sure Degale get's hit but never kinda flush, I think his chin and movement in general see him survive and GGG get increasingly frustrated. By the mid rounds, it's a cake-walk for Degale. UD. Just my take....you may well be right.