Indeed, he just won't be able to bring both to endgame, he can still field both when they come around and aren't required.
Hmm and as far as this playthrough goes when it comes to Dheg, Leonardo's 3-range will help, have Sanaki (if you do use her, I'm not sure if you'd bring her since she's required to bring but not field) bless bolting/arcthunder and pelt him. Oh and did you forget about Kurth or did you use him last playthrough? If you can use him he'll be amazing too. I must say though, once she gets over her transform issues Lethe will probably be a godsend in endgame. I'm using her in this current playthrough (my own personal favorite units) and she is wiping the floor with endgame so long as people use direct attacks on her (obviously). And well I'm not too sure about the other's speed caps, but so long as they don't get doubled by Dheg then Makalov/Meg should be able to take a hit, Marcia too will be rather invaluable in hit-'n'-running him.
If someone stands in the way of true justice, you simply walk up behind them and stab them in the heart. -Ra's Al Ghul / Henri Ducard, Batman Begins