There's some third-party clients similar to what Twitter had this time last year, with Apollo being the most popular to the point of having its icon/screenshots in Apple's WWDC presentation last week.

I think the biggest impact, though, is some moderators rely on tools/clients to make their (voluntary) jobs easier. If those tools disappear, then a lot of these subreddits will probably shut down for lack of moderators. And I heard that /r/blind mods literally cannot use the existing Reddit site/apps.