More to the point you don't turn up at a clubs cup game against a lower league side if you aren't happy to sign.My guess is either his agent wheeling for some more cash at the last minute, or more likely there is still some disagreement about a recall clause in January.
I have never seen Wilder be so open about signings being done in an interview before though, so I would be amazed if this falls through now.
I don't know because I'm not a club owner like quite a lot of people on here are (I assume anyway with way they're going on) but I'd wager with Palace wanting to make sure he remains theirs, make sure he gets game time, make sure he can be recalled etc on top of what his agents want, on top of what we want AND then let our social media team tit about filming some ridiculous reveal video, it's going to take as long as it takes.