We could add an analyzer based on spaCy. It would enable support for some new languages and possibly also give better results for eg English and German than the current snowball analyzer.

Getting the full benefit of spaCy may require some internal API changes because it is more object oriented than NLTK and processes whole sentences instead of just individual words, taking some of the context into account.

This would be an optional feature as spaCy is implemented as a native code extension, not just pure Python.