Profitability is a key factor; Nick may have few real successful cartoons around, but with Spongebob’s and TMNT’s popularity they generate enough revenue to be self-sufficient. So they’re not hurting for money.
With the internet in it’s current state breeding fans which increases viewership thanks to devoted fanbases from all over; Helped MLP, Adventure Time, etc.
The number drop is a mainly due to live action, IMO. Both Nick and Disney (and CN for a time…ew) having been pumping out Live shows taking a share of the air space normally used for other toons.
@Virgil Stormblade
according to some sorces alex hirsch had to argue with disney suits over the contact he was allowed to show on gravity falls on CN most of those things would have ok under a TV-PG rating