Judging from what I have been told, it is possible to gain another hand in height fully grown to what they measure as a 2 year old. I would definitely expect another inch or two! **points and laughs - giant horse**
I use to be at a yard where the YO bred welshs with her own stallion and broodmares. The stallion was 15.3hh and one of the mares was 15hh. Out of those two, they use to always throw a 14 - 14.2hh pony when fully matured (they kept the fillys for themselves). One year the same pair had a colt and sold him as a six month old. This chap made 16.2!!! YO has still got one of his full sisters (same parents) which is 14.2hh!
the old saying " a hand on a yearling, and two inches on a 2yr old" but then there are always exceptions to this! sounds like yours should make 16.2/3 maybe?
My boy is by a 16.2hh danish warmblood stallion (confirmed) out of a 15.2hh dapple grey mare who was thought to be cob, irish draft or percheron type. Bentley is just four and I last measured him several months (and inches!
) ago at 17hh
I've decided not to measure him anymore
ETA he had a very poor start and I think (hope) the inches are muscle mass and not skeletal growth!