Gio and Valimaki are pretty much pencilled into our top 4 whether we like it or not.
We also have Gustafsson and Forbert as LHD and I wouldn't be surprised if at least one of them is retained (at least in a vain effort to make the picks worth it)
Kylington's been identified as a weak link and pushed out of the line-up two years in a row and Hanifin was reportedly part of the offer for Hall. Not sure it's wise to be too attached to them
Kylington is a young, raw talent that they didn't feel was ready for the responsibility of games with no margin for error. With a veteran, being replaced like that would absolutely signify his expandability. With a young player, not so much. He still has to earn it, but he's going to be given that chance.
By the same token, by no means can Valimaki be pencilled into anything until his play can be evaluated after the extended absence.
A lot has changed since Hall got traded, including Hamonic's value likely tanking in the eyes of the Flames given how his absence seemed to help the team. With Brodie gone by all accounts, and the Flames hopefully realizing Hamonic's flaws and moving on, there is a huge need for both of those guys to take the next step for the Flames. I think it's unlikely that they opt for Gustafsson at Kylington's expense given how close in his development the latter is to being as good or better than the former.
Right now, the only defencemen we have committed to as NHL players next year are Giordano, Andersson and Hanifin, with management really hoping to plug Valimaki in as well. That's still two completely wide open spots and many different ways to fill them (likely a big part of making Calgary an attractive destination for these two college guys). So to say anyone from that list or the bubble is as good as gone is a bit knee-jerky to me.