Well, I called
Disneyland Guest Relations.
The conversation went something like this:
"Disneyland Guest Relations, may I help you?"
"I have some days leftover on a Disney World Magic Your Way ticket. Will I be able to use those for Disneyland admission?"
"You mean a Hopper Pass. Yes, we take those."
"Well, I know you take the Hopper passes, but Disney World changed it's ticketing to Magic Your Way and I was wondering if you'll take those."
"Well, I don't know what this 'Magic Way' is, but we take unused Disney World admission. I can't guarantee it over the phone, because if we have a question we call Florida and ask them."
"Thank you for your help."
"Thank you for calling Disneyland."
I don't think that answers any questions (except whether or not Hoppers are acceptable admission to Disneyland

) so if you'd like to try for yourself, Disneyland's Guest Relations number is 1-714-781-7290.