I think his name will be Aemon. I believe that they did not want to confuse viewers with Maester Aemon from Castle Black hence the switch to Aegon. For the same reason they created Yara Greyjoy.[MENTION=23751]Maxperson[/MENTION], Cool! Glad to hear it.
On Aegon, I think it is going to be Jon even in the books, 'cause I guess the other claimant is going to die horribly before the ending