If you haven't seen him you have seen NOTHING!!
A couple of carrier battle groups with F35s, a dozen or so nuclear submarines etc etc were routine procurement plans.
Anyway, lets stick to the topic now.
bss AWAIN!!
ON a serious note, we have the capability to produce 7.62x51 rounds and there is a whole plant dedicated to it. Plus army do love its "over kill" capability. It is likely that we will go for two calibers, both x39 and x51. However i do agree that x51 do not offers much over x39 and it will be ideal if we can standardize the ammunition and go with one (which then SHOULD be 7.62 x 39mm and not x51) but the fact remains that we have huge stock piles of x51 and a well oiled setup for manufacturing the same, wont close that. Plus the NATO connection cannot be ignored either.
To conclude from my side, it is likely that both x51 and x39 will be selected, separate rifle for both. For battle field rifle, we will stick to x51 and for assault rifle and CQB we will go for x39.
However, if ONLY ONE have to be selected then it should surely be x39.