Fun: it took a while to get used to the controls, but after an hour my trade routes were set-up and running again (2 Mercuries and 2 other medium freighters), safely [I hope] guarded by a fleet of small to medium fighters. I ended up going after the Nova in the 2nd Unknown Territory: apparently one of my savegames was geared to get that one. I had given up, I guess. The only way to get there unharmed is to get a fast fighter (Discoverer or the Boron M5 class ship I forget the name of) with a jump device, go in, change ships (while exchanging freight) and jump out in the Nova to Grand Exchange. The Discoverer I considered ‘scrap’, but apparently made it out unscathed too.
I’m not sure if EgoSoft (the maker of X3) is planning to create a succesor to the game: it doesn’t look like it. Their website only lists 2 extra bonus packs (including XTM, which I might try) and for the rest, the forums seem to be geared to modding only.