Ihor Radchenko <yantar92@posteo.net> writes:

>> I think, verbatim option should not be removed from `defcustom' :type 
>> just now. For some users it might cause fallback to raw lisp value in 
>> easy customization UI. Perhaps another warning should be added to the 
>> `org-set-emphasis-alist' validator and the option should be labeled as 
>> unused in the :type definition.
>
> Makes sense.
> What about the attached patch?
> The idea is to tag the constant as deprecated.

I further improved the patch adding variable watcher. This should catch
everything. See the attached.

Let me know if there are any objections.