Technically, they CAN make a Spectacular Spider-Man Season 3. And what I mean by that is something that takes place right after Season 2 timeline-wise. However, everything would be completely different. The art, voice acting, tone, style, soundtrack, etc. Everything would be pretty much different and the only thing it would have in common with TSSM is that it takes place in the same universe timeline wise. And even then, it wouldn't be an exact continuity but more of a loose continuity, and references to stuff that happened in seasons 1 & 2 would be very low. There is no point in making a "season 3" at this point because it would be a completely different show with a completely different feel so you might as well just make a new show. Unless Marvel magically gets Greg Weisman, all the writers, and all the voice actors back but the chances of that happening are less than 1% from a business and legal point of view. And even then, chances are that it will still feel like a completely different show. It's almost 100% pointless at this point to continue TSSM as a TV show (a follow-up comic like Gargoyles or a follow-up DTV like the DCAU Batman movies are different stories). Personally, one side of me would prefer if Spidey takes a break from animation for a couple of years but another side of me also wishes for another great Spidey show not only because I'm a big fan of the character but also because a great Spidey show coming out right after Ultimate Spider-Man's cancellation (which will hopefully be after season 2) and topping USM in ratings would be the "ultimate victory" against USM. Nothing would add more salt to the injury and prove to Marvel how stupid it was of them to create this show but that.