Either they believe they are getting him off quota. Or they already have an English centre and halfback tied down (King and Pryce for example). I don't think that's likely to be the case if I'm honest, but I don't think we can judge this one fully until all signings have been announced.
Bell is a good player, I'll be happy to have him, but I agree we have other roles that need filling more urgently.

I think he signed an 18 month deal last season. 

Was originally announced as an 18 month deal when he signed, but he mentioned in August last year he still had two years left until 2026 so maybe he had an option which he chosen to activate when his dad came across.

https://www.google.com/amp/s/www.hulldailymail.co.uk/my-bookmarks/jed-cartwright-makes-hull-fc-9483339.amp

Definitely announced he signed an 18 month contract, but I've read someone he had 2 1/2 year deal and not mentioned by Dan he is OOC, so guessing he is here next year.
Hope the rumour about Pryce is true, then we prop and outside back (of similar standard to what we already signed) and I will be feeling pretty confident about next season.
If we are willing to pay a fee I'd make an offer to Fenton Rogers at Hudds for the prop position.
Also agree with others, think there will be other movement within the contracted players maybe even a quota player, Myler has shown he isn't scared to make tough decisions.

The difference this year is the quota players are all performing well (so far) and we'd be significantly weaker if any were to leave. Makes a nice change! 

I'll believe the Pryce deal when it's announced. We were told that Cross was a done deal.
However next year I imagine the home shirt will be a take on the 2016 white shirt / black V for the 10th anniversary of the Cup win and you can picture the club using a photo of Leon in the 2016 shirt and Will in the 2026 shirt. Would be a good story for sure.