No, not really. Volition brought us Saints Row The Third. THQ just published it. All the development houses under THQ's wings can be bought out by other publishers. It is highly unlikely that such high profile devs will simply be left to disappear.
Yep, I still have an issue with the new Saints Row when there is an internet connection present resulting in co-op being totally unplayable for me, and Volition refuses to address it despite at least 100 other people on their forums reporting the same issue, yet they pump out DLC content pack after content pack.
Oh great... so we'll still (hopefully) be getting Saint's Row 4 then someday. I'm feeling much better now.
Have never tried SR in multiplayer though. How does it work? Do you help someone on their campaign or do the come and help with yours? I'm not very big on multiplayer so I have no idea how things tie in.