Ideally Tibet as a buffer would be great but that window of opportunity is long gone we had the chance in 1950's but we had Nehru & his bunch of clowns, now any such attempt will lead to MAD (mutually assured destruction). Even Taiwan's ROC will not give away Tibet if it comes to power after CCP falls. Frankly next Dalai lama will make sure CCP's get what it wants from Tibet. CCP is the root of all problems here.
Not gone..... Trust me history is in making... Just wait for 5-7 yrs
MAD couldn't save fall of USSR...
Let me tell few things to draw a parallel between China & Russia-
USSR was great military might, far far stronger than what china is today but was without economy & on the other side China is greater economy with lot of clout but militarily not a power to reckon with, on top of it it is ruled by CCP with its nefarious agenda. Point is they are not complete power like US, china's ambition will remain in paper of becoming superpower until they don't build a unmatchable military & keep growing economically.
Post-Wuhan spread China finding it hard to maintain its economic prowess, anti china sentiment is all time high accross the globe, adversaries forming alliances with only one objective. So where all this leads to... In my reading to same point, fate of USSR....
A caveat- If India maintains good economic growth, put it's house in order, keep building military, be at fore on geopolitical issues, I don't see any reason for why India can't wreck havoc on China without firing a shot. What happened in Galwan had happened in bit larger scale with 700-800 casualties of PLA bats, that would have set things in motion, enough to create turmoil in CCP & China.
What do you feel why they didn't attempt to avenge Galwan & rather chose to underplay?