in a couple of years the 25th anniversary of Warhammer 40,000 will be out. For the 25th of Fantasy they released a 'Harry the Hammer' model. what do you think it will be for 40k?
in my honest opinion i think that maybe one(or more) primarches will return from stasis or where ever else they are. Russ and Corax are in the warp, Khan is in the webway, Gulliman and The Lion are in Stasis, etc.
my thoughts is that it is Gulliman that will return seeing as the ultramarines are the epitome of the astartes and also he is rumoured to be recovering. (primarches are made of some tough shit eh?)
i don't think the emperor should come down from the golden throne or be reincarnated as that would kind of ruin things a little in my eyes.
or maybe even a primarch as a daemonprince for you chaos bastards