So how would China develop if there were no unequal treaties forced on them during the 1800s like no Opium Wars, no Eight-Nations Alliance, not losing Outer Manchuria, etc; maybe just losing Korea and Taiwan to Japan.
It likely has no incentive to modernize until a rude awakening happens. It would still slowly see Qing rule stagnate, probably.
A lot of this depends on why aren't the various humiliations happening.
The Qing would have more time to sort out their various issues (corruption and a bureaucracy that hasn't been expanded since Ming times IIRC), but they'd still have a very hard time during the 1850s, with the Yellow River floods and the Taiping and Nian rebellions.
