Interesting idea, although I don't really expect that would ever happen. The majority of Spyderco's collaborations are with small custom makers (with the exception of the Lionspy), and while Mick Strider does have his MSC line, the majority of Strider knives are widely regarded as productions not customs. Additionally, what do you think a Spyderco/Strider collaboration would look like? An SnG with a round Spydie Hole? Seems kind of pointless if you ask me.
All that being said, I'd love to see Spyderco put out a well designed, over-the-top, over-built knife.
The Tuff is sadly discontinued, so in my opinion, they really need to fill that gap. Also, what are the handful of other knives you mentioned? I really can't think of any that are similar to the Tuff.