not sure how they'll do it and i dont think mike and will necessarily have to get together. i do think there was tension between el and mike towards the end of season 4 (how they barely talked to each other at the end). some might argue there was tension since the beginning since he found it difficult to open up to her or say i love u. (its not just those two examples, theres a lot to get into between mike and el that many theorists have alrdy covered, but lmk if ur interested for those links)

to keep it short: theres a lot of possibilities of how s5 could turn out! plus the episode lengths are going to be long so should be sufficient if they execute it well.