Uh, Crytek, isn't it kinda YOUR job to MAKE interest higher? Perhaps you could just focus on making a fantastic game that can be successful on it's own merits, rather than try to coast on the nostalgic interest of the fans of previous installments.
I don't think it's unreasonable to rely on a pre-established fanbase to make up a chunk of your sales, but when you keep a series in hibernation this long, you can't fairly expect the fanbase to have just been sitting on the edge of their seats this entire time.
Honestly, just make a great game, advertise it well, and the fans will come, both old and new. I know that's FAR easier said than done, but its probably your best bet.
(An HD collection wouldn't hurt either)