Does China need Tibet, Ladakh, Arunachal Predesh, etc.?

Not at all, apparently you're obsessed with Pakistan's involvement which is a remote possibility. Pakistan is so much damaged & devastated after 9/11 as its after effect that it will have to wait another 15 years to rebuild to recover to pre-2001 position. Most of Indians indulge in day dreaming & come out of a new theory of Indo-Pak war somehow as shown in many dozen Indian Hindi films too after 1999 but no such thing happens. Military build up & movements are NOT child's play. Both Indian & Pakistan armies are very much tired a lot in last 20 years needing rest.