Also, Rumple is a character whose cunning is not dependent on magic (as we saw with Mr. Gold in S1 before he had magic)
In season one, yes, he was not dependent on magic. Season 2 and onwards, he is more than dependent on magic now. He’s obsessed with it. Rumple has an addiction. And I think that he still thinks he can have both magic and Belle, but he can’t. Belle showed him that he can’t. But his quest to find the author in 4B, I’m pretty sure will about finding a loophole (because Rumple is good at finding those), a way to have both Belle and magic.
I’m not sure if the culmination of this arc will be removing Rumple’s power through true love’s kiss. I think that would be better saved for the final season. I think Adam and Eddy plan Once for at least 7 seasons, I think, so the end of the series is a long way off still.