Will Omega from Mirages of Omega be released in Meta?
Search 
function is your friend.
All the available info about the mirages of omega you can find in here . 
Well that thread doesn’t specifically answer OP’s question
The answer to OP’s question is nobody knows, and Omega has not appeared in Beta testing, so at this stage probably not. It might happen that Omega is added as a hero at some point, but there is no evidence right now to suggest it will
Please use above linked thread.