If Trump and Cruz should announce they are pooling their delegates together, it will very difficult for the GOPe to not give the nomination to Trump.
Why would Cruz do that? Because, if it looks like the GOPe is going to jump through these hoops to give the nomination to someone other than Cruz (which will be the case) then it would benefit Cruz to join forces with Trump and ensure Trump gets the nomination (in return for the VP slot).
Cruz really has nothing to lose under that scenario, and something to gain.
Unless, Cruz believes he can run again 4 years from now and win the presidency (which I don’t believe is the case, but what is important is what Cruz thinks).
Cruz can run in 8 years. Reagan started running in 68.
Problem is they cannot pool their delegates. The delegates are committed to Cruz or Trump on the 1st ballot. After that they can vote for whomever they desire. Just as the delegates committed to Rubio, Carson, & others are committed to those candidates on the 1st vote, even though they have dropped out.