I've speculated and dreamed a bit on this one, myself. ;)
Giancarlo Esposito and Emilie de Ravin for Mykkael and Anja. Not sure about Taskin... it's been awhile and he hasn't stuck in my head as well. Fun question!
Yuen Biao and Milla Jovovich
...When I saw that official art of Mykkael and Taskin, I could think of three actors to play Mykkael: Djimon Hounsou, Wesley Snipes and Denzel Washington. ...Denzel's got the advantage that he REALLY doesn't look his age (he's 58?).
As for Taskin... hm. I think Jason Isaacs would be good. Whenever Isaacs plays a villainous or otherwise aloof role, his eyes make him look very icy and controlled - just like Taskin. Just seeing him in The Patriot is enough proof. http://www.imdb.com/media/rm1015848192/nm0005042
A younger Charles Dance would be a good Taskin, but he's likely too old now.
He is a superb villain (as the notorious solicitor Tulkinghorn in the recent BBC adaptation of Bleak House, he was sublimely evil), and he is currently playing Lord Tywin Lannister in Game of Thrones (which I do not watch.
He has played good guys well too, namely the sarjeant in Jewels in the Crown, investigating what happened to Harry Kumar in the aftermath of WWII in pre-independence India.