Eh... nah, I don't see that happening. I think it's safe to assume that CN will never have an equivalent to Spongebob. At best, they can hope for something to reach the same popularity level as, perhaps, The Powerpuff Girls or DBZ at their respective peaks... but not Spongebob.
Spongebob is a massive media/merchandising conglomerate, in a league all its own. We'll never (yes, I say never) see a CN series reach the kind of level that's on. Undoubtedly, part of this comes from having a company like Nickelodeon/Viacom in your corner, whereas Turner doesn't seek the same kind of output from their animation network. Another part of this also comes from CN's self-imposed term limits to their programming, whereas Nick doesn't care about the quality of the product, and will just milk that series dry until the end of time.
It's all the same, though. It really doesn't matter that Spongebob's overall episode quality is substandard nowadays; the series, its characters, and its merchandise is still absolutely huge, more so than anything CN can ever hope for. It's basically on a whole different level than any of its animated counterparts. CN just isn't a big enough brand to create something like that... and, as I mentioned earlier, their business practices kinda prevent that from ever happening, anyways.