AbuseFilter has become quite critical for maintaining projects, local hits on enwiki alone can hit 1 edit/second during peaks, and edit filters have been leveraged to enforce community policies and standards not otherwise possible. I recommend WMF allocate funding to ensure this is maintained.
Topic on Talk:Code stewardship reviews/Feedback solicitation/AbuseFilter
+1
Abusefilter is definitely something money must be spent upon. It's pointless to talk about user retention and anti-harassment while removing the most effective counter-vandalism weapon.