well, i'm sorry. but your comment seems difficult to be followed. correct me, if i get you wrong.
I dont know how your scenerio is plausable. Tibet is a free area to fly in expecially if your flying at high altitudes,and the intercept time for Inaf would be far less.
mind to explain a little bit about this, why? are you suggesting that the SAMs and intercepters are nothing but toys. and far less intercept time is an advantage?
Those bombers would either get shot down or the cruise missiles will.
how? the bombers can launch their missile 500-1000km away from the india border. as to the cruise mussiles, yes, some of them will be shot down but not all. and they are so cheap compare to their target's value or even that of the intercept missiles. so mass production is not a problem. on the other hand, it will take time for India to import the intercept missiles if they are still available.
If the Inaf dicided to strike the PLA the would in Tibet cutting apart their supply line. You seem to assume the PLA would have it easy when it come to air warfare against India.
i think you meant IAF can cut the supply line of tibet, right? and yes, that is possible. the question is a) at what cost and most importantly b)for how long.
and i never said that it would be easy to counter the IAF, what i said was the PLAAF can, despite with some or even heavy casualties. bacause they got the upper hand in logistic and reinforcement.
The PLAAF wont resort to an offensive because much of their time would be left on the offensive because of Tibet and the high altitude. If the PLA wanted to strike India, they would with ballistic missiles. The one thing that is sure to work. You assume things that are wrong. You assumed PLAAF can sustian operations easily in Tibet when in reality they are hampered with quantity! So how are they going to use there advantage?
i think you meant "defensive". actually PLAAF knows that too, so no bombers were deploied in Tibet, just intercepters. All bombers will take off from the middle or eastern part of china. and, again, they will launch CMs not BMs.
If the Inaf dicid to escalate the war they can bring the fight to Tibet but the reverse is nearly impossible infact sucidal given the friendly home front advantage of the Inaf.
for how long you can bring the fight to Tibet will depend on how much airport, airplanes and ammos do you left.
And what makes you thing the PLAAF will be an offensive air force? when was the last time they droped bombs like the Inaf did to Pakistan in 1971 and Kargil?
PLAAF is not an offensive air force now, she is a defensive air force with certain offensive capability (she has strategic bombers, escorts of the bombers, refuel planes, but not in large quantity compare to US or Russia).
Indian also rely mostly at imports from other countries while china always try to find solutions at its own.. anything at which china faces difficulty in acquiring, china try to develop it at its own. 
