I'm fairly certain the rest of the Turtles will get in DLC anyways, so it's no biggie. Besides, I'm rather curious to see what they will do for the Rugrats exactly, seeing as they conspicuously went with Reptar and Teeter Totter Gulch of all things to represent early Rugrats. I think the DLC will be a mix of series in the base game and unrepresented ones. To me, ARM and Thornberrys aren't strictly necessary to fill up, since they seem like one-shot deals.
In regards to who I want, at this stage I really just want Shredder, Daggett, Kitty, Jenny, El Tigre and maybe a couple more Loud sisters.
Though for one comment I saw in the Twitter post from earlier, there's one fan that was...less generous and impatient. They claimed that Fraymakers is better.