I'm ok with cutting Cushing, Allen and Miller but if I could get anything for these guys in a trade, I'd do it. A lot of teams could get nostalgic and trade a better than expected pick for a savvy veteran that may gap a position. Bottom line, the Texans are in need of additional cap space and picks in 2018. Will the team get the same cap relief if they trade these players versus giving them an outright release? If any of these 3 guys returned a RD5, I'd do back flips and hail the new GM as a mastermind, but in all reality, if these players returned RD6 or RD7 picks, I'd be a-ok. The draft is really deep in DB's and having those extra late picks could be of some benefit in stocking the ST unit.
As far as KJax, JJo and KJo go, their success has always been dependent on a solid performance from the front seven. I'm thinking there will be enough healthy bodies returning on defense that the defensive backfield will once again look good. I still think that one of the best moves available is having KJax play FS. He has to play defense facing the play, then be allowed to use his speed and physicality to be the disrupting factor. Texans could use the extra cap space to sign FA, CB- Morris Claiborne to allow the KJax position move. The draft is where the Texans would need to find a big and physical SS in the range of 6-2+ @ 220+lbs who has the ability to be a factor in the running game and still be able to cover the position in the passing game.
I'm going to wait on the offense discussion since there is so much to look at in terms of need(s).