Although I'm not an elite with UA, here's my feelings on certs. They should be non-transferrable, but you should be able to use them for a companion traveling with you, so going to electronic certs does not affect this (unfortunately on my airline of choice they are non-transferrable period ).

UA should talk to DL, because from what I saw DL did not have any problems with the transition. BTW, if they do decide to do this my recommendation is spend all your paper certs you can before the switchover. What DL did was just replace all non-expired paper certs, regardless of whether or not they had actually been used. Obviously exchanging paper for electronic certs would have been a giant pain in the butt for the airline!