Best of luck to Horton if he indeed moves on. He's worked hard and improved every year.
Wasn't a great idea to only play 4 WR when 2 of those were seniors, 1 nearly portaled last year (Horton), and 1 was viewed as 1 yr rental regardless of how he performed (Brown), now was it?
Will say, I don't think it's a great practice to get into a bidding war to keep a WR like Horton. He's been an outside possession receiver - a more productive one who has a much better attitude than the guy he replaced (Young), but a possession receiver nonetheless. He didn't produce much the last 3 games - 10 catches for 68 yds & 1 TD (long catch of 14 yds) - when he replaced Sam Brown as the 3rd WR. I have no idea if the coaches think he can develop into a consistent downfield threat or not. If they do, then you do everything you can to keep him.
However, similar to the JHH situation last year, poor rooster management at his position almost necessitates keeping him. Otherwise you have to replace him 2-for-1 in the portal like we did with JHH (Barrow + Cook). Barrow for JHH was a trade we won on, but we needed disruptive DTs even if JHH had stayed and Cook was a dud. We appear to be in the mix with a multiple very good outside receivers, so perhaps the 2-for-1 will work out for us this time, but this is a tough situation to be in when you're also looking for a portal QB.