The reason why I pick up AoSTH is because Sonic Boom has more in common with AoSTH than it does with the rest of the past Sonic cartoons. Primarily both cartoons are catered for a younger audience. Granted tthe executive producers have a different concept of what is good for the modern audience than AoSTH had for it's time but still both shows relatively have the same chemistry.
If it was instead SatAM who have the first crossover, well the freedom fighters will have little in common with Team Sonic.
Boom Sonic: You dunno what it's like to have some guy attack us with robots every other day, trying to take over our island.
SatAM Sonic: My whole world was conquered by our version of the "some guy". He robotisizes his captors, a fate worse than death, converting their living bodies into mechanical flesh, making these victims the prisoners of their own bodies. He already won the war. He posioned our lands, and covered the skies with smog just because only he can survive in such toxicity. All we can do is fight to reclaim our world and restore it to how it was.
*Awkward silence between SatAM freedom fighters and Boom Team Sonic*
Eggman: Anyone tries that new humus place? It's actually really nice.
Maybe if instead Team Sonic were invited onto SatAM Mobius just to see how bad it can truely be in comparison to their world and actively help out the Freedom Fighters for an adventure, then not only would that introduce more interesting dynamics but leave Team Sonic an aire of maturity.
Sonic X may have more in common with Sonic Boom but not by much. Sonic X is to a degree more faithful, or at least "accurate" to the games and Sonic was more lazy and aloof.
I know I sound like Nidza who goes on about another season of Sonic X or TMNT crossovers with Sonic Boom, but I assure you that if there was at all any chance of Sonic Boom having a crossover special with any of it's predecessor cartoons, AoSTH would be the most compatable with Sonic Booms genre and formula.
And I know it would be possible! That new Cartoon Network show "OK K.O.! Let's Be Heroes" had a crossover with DiC '90s cartoon Captain Planet! I'm sure Sega and Technicolor Animation Productions could negotiate with DHX Media for rights for such a crossover to be pulled off!