There is no indication that they will remove apps wth more than 50 characters, I think their algo will handicap people trying to stuff keywords in their search. I'm noticing it in the last few days. Also the 50 character limit seems nature to implement during review. The App Name field in iTunes connect will shortly cap at 50 characters and the next time you want to update, you will have to comply with that.

Keep in mind, there are two different concepts, quality of apps and app name length. The quality of apps is one where they will run through their inventory and judge if they shall be removed or not. A 30-day notice will be given. The app name length in my opinion will likely be a next update thing, maybe unless some users are really squeezing the limit, they might get an individualized take-down. I highly doubt they would do major take-down action regarding app names. More likely to handicap. PS We will not likely hear anything regarding this during todays keynote, as it don't really concern the general public. A general mention of the App Store cleanse, but no specifics.