Over at Inside Texas I have an article available for free on what personnel Herman needs to find, add, or develop to get Texas going in year one.
Sounds like replacing D'Onta Foreman will be a major priority. I've been identifying three components as being crucial to Texas' run game dominance in 2016. The RB D'Onta Foreman, TE Caleb Bluiett, and the left side of the OL who were anchored by LT Connor Williams and then quite good with either Jake McMillon or Patrick Vahe with him at LG.
Two of those three components are gone, but the one returning (the left side of the OL) is probably the most valuable and essential. Now Herman just has to fill in the other two spots.