Hmmm... well Samurai Jack is getting a new season soon so I don't need to worry there.
Both Thundercats and He-Man had remakes but both fizzled sadly (I'm more sad about Thundercats tbh). She-ra might be a good one actually.
Lastly, I would have LOVED to have gotten more Batman Beyond. Cyber-punk batman was such a great idea, too bad it got cancelled early in season 3.
That's all I've got right now for American cartoons.
As for anime...... Great Teacher Onizuka, Yokohama Kaidashi Kikou, and Berserk could use remakes because 1), G.T.O. leaves waaay too many great moments out! 2), YKK is just such a fantastic anime that the OVA, while very good, left too much out. And 3), Berserk's original anime series perfectly captured the tone but again, left waaay too much out and definitely could have gotten more season out of it before a certain moment.