Does Indian tourist destinations which you mentioned like Shillong, Chail etc have international stadium already built there ? If they already have the stadiums there, then they should host the international matches there.
As far as Pakistani cricket stadium is concerned, its newly built and i am hopeful we may see some PSL matches there in 2022.
Shillong used to be the capital of undivided Assam. But once Meghalaya was separated from Assam, it lost its multicultural image. Nowadays ethnic clashes are very common in that city and the locals are not very fond of outsiders residing there. They even prevented a proposed railway line, saying that it will cause outsiders migrating to Shillong. And you can assume what will be their reaction, if there is a proposal to upgrade the Shillong cricket stadium.