The sooner the Shuttle is abandoned the better. If the shuttle's low performance begat the low orbit space junk of an ISS and that low orbit allows a private start-up to get its leg-up into the market, well, maybe that justifies some small part of it. Maybe also the lousy level of engineer-based systems that the sucky Shuttle program decayed to is itself helpful, as it created a internal-to-government bureaucracy socio-technology vacuum block, a gap, for a generation. In other words it blocked the government from doing something better, but not as good as private biz will do.
It must be remembered that Shuttle payload and optimum flight profile were not built around where the ISS is orbiting. Bad Bill clinton had his own Russian Outreach Program that put the ISS in a waaay northern orbit that cut Shuttle payload by something like 1/3 to 1/2. Typical dumbass Bill clinton diplomacy.
For the single thing that actually was a went-as-designed mission and piece of hardware, there’s Hubble.
I wish now that NASA just got their bureaucratic butts out of the way and let SpaceX and the rest of them at the skies.