"When Alexander saw the breadth of his domain, he wept for there were no more worlds to conquer."
I think part of the problem is that you've achieved pretty much everything you wanted to in EVE regarding your chosen specialty, heck, you've pretty much defined and served as the inspiration and model for it. It might be that you've simply run Istvaan as far as the character or the game will interest you.
It happens, and sometimes its simply grinding metal to try to milk joy out of a character when its just not there. A writer once told me, "always plan for the death of your characters, understand that it will happen, it makes them far more enjoyable, and makes you care for them more". Sometimes, the best way to continue to enjoy a remarkable characters story is to plan for the end of their story.
If youre having fun being a noob corp again trying hard to earn enough for a real T2 ship, then by all means, continue. Teaching and experiencing familiar things with people just beginning is a good way to rediscover what you loved about an endeavor in the first place.
Or, go for the knowledge thing. Try to discover it, or even create it (in part anyway). Part of what I think is fun about EVE is that so little of the knowledge is actually defined by the Storyline team, and I'm more than a little certain they look to a lot of the better player-written fiction out there to indirectly expand and refine and color the EVE universe. You obviously know a lot about the EVE universe, both its PF and its "human" element, so writing and expanding a bit on the frontiers and grey-areas of the EVE storyline could be fun, as well as a nifty way to leave another mark on the game world and game community.
Or, if you really wanted to go out with a bang, take a page from Andrew Carnegie, and resolve to have Istvaan biomass penniless, and simply see what kind of effect 21 Titans worth of ISK can have when spent on whatever inspiration might take you. While Carnegie gave to charity, what Istvaan(c) would see as a worthy cause would be interesting to say the least. Kinda a "here is my stuff" except that stuff is in the form of bribes, mercs, alcohol (its been done, in the billions!), and general chaos, or possibly even a semi-noble cause, or all of the above.
Whatever you do, you've certainly left your mark on the game.
P.S. if youre really bored, could you find a way to lower nocxium prices in the Republic? I know a couple pilots in my corp who would be thrilled.