The options at SF parks last year were all houses for one night or all houses all season for a bit more. Best I can recall about $35 and $47 at the in-park kiosk.
If KD gets this, it will still be a better deal than SFA Sunday night because that was only 3 hours to do everything. I got in all houses but rode almost no rides. GrAdv was the same price though, for a lot more, still only 4-5 hours to do it.
It wouldn't make sense to charge single-day ticket holders for houses too (unless tickets are super cheap), and then not charge passholders (except Prestige?). If they don't charge for CF houses, I'm paying less for all CF and SF parks than I was. If they do, KD all-season Houses adds about what I was paying for a legacy SF Membership before they raised the price, and 2 parks of new upcharges is about what I'd be paying.
As to Winterfest, Christmas Town used to be an upcharge for passmembers, but cheaper for a day pass than regular season due to reduced offerings. WF never did make much economic sense and if it was an upgrade, they could offer a free one for renewing/buying a pass early.