The key point will be that the 20 saplings are all grown from seed, and from seed selected from as wide a parent population as possible. Given those circumstances the genetic pool represented in your sapling sample will be as wide as possible given the natural variation in the species pool. To take the contrary view, say your seed was selected from 2 cones from one tree where there are only two trees to exchange pollen. All of the seeds produced will then have a genetic pattern that will be as restricted as you can find.
Given an inherently wide array of genetics in your 20 trees you may find a couple that will survive the heat. These could then go on to parent other offspring. Of course, you could apply the same thinking to breeding a banana plant that would survive in the Arctic which is clearly unreasonable; however if the seed comes bulk collected from a forest in Pakistan then this puts you back into the realm of possibility. There may already be some trees in countries with native populations of Deodar growing in the hotter limits of their range, with some of the selection already done for you.
Existing cultivars will not be much of a guide to the possibilities since they will have been selected on the basis of very different criteria.