52 is the, "magic number" for most animated series divides into 3 seasons nicely (unsure if tfp tallies up to 52 EPS.) If a series goes longer than 3 seasons its usually successful e.g. spongebob, teen titans and the Simpsons.

There's is some debate on other boards if the new series will follow on with the prime continuity, I think it will but the new movie will probably form part of the series backstory.

Others have been praying for that fourth season of animated. I don't see that happening.