Nothing new here, not hard to fill the block
alot of people will be upset if the halving block had no transactions in it and all the "messages" ended up in the next block
Well, too bad It's a "risk" that people face. It's also possible that blocks 419999 and 420000 are mined a second apart... Pretty much anything can happen, thus why I think not many people will really be bothered to point their transactions to the halving block.