Blaserman: Nothing - many of us still around.
I currently own 13 (thirteen) Rifles in caliber 220 Swift. Four of them are mint condition pre-64 Winchester Model 70's in my collection (in three different models) that I do not shoot and the other nine I shoot - mostly at Varmints and predators.
I missed buying a minty Remington 700 stainless heavy barrel Sendero earlier this week - I missed it by one day - thought about it 24 hours to long (price $899.00).
There still is a "niche" market for Rifles in caliber 220 Swift just not much in the way of supply! When a clean (with good bore) used Rifle in 220 Swift comes on the market, in my experience, it doesn't last very long.
The 220 Swift Sendero I just "missed out on" was on the market (gunstore rack) for 2 1/2 days!
Many of my friends that I Varmint and predator Hunt with own Rifles in 220 Swift.
I have a fair supply of 220 Swift brass on hand so I won't be leaving the ranks of 220 Swift "fans" any time soon.
Long live the 220 Swift.
Hold into the wind
VarmintGuy