My clutch cable appears to be stretching to the point I put a sleeve between the adjusting nut and the actuation lever to make it work. Am I wrong in thinking this may be the beginning of the end for the part and that total unraveling my be in the future?

No you're not wrong, get a spare cable now.

It may be a broken clutch tube attaching point in the tunnel.
Buy yes get a new cable. If you do have to repair the attaching point you want to use a neew cable.

Driving without a clutch cable is not fun....Possible, but not fun. Get one now before you have to test the ^above ^. They are not expensive and can be installed with simple hand tools and a floor jack in less than an hour

I had to adjust the clutch cable several times before it snapped. As others said, if the clutch tube is secure it would be a good time to buy another clutch cable.

I second this

and not really hard to replace the clutch cable.

Related question. How much does a new cable stretch before it settles down? I have a new cable from Porsche and I reinforced the clutch tube attachments during my resto so am pretty sure that is good. During the first couple hundred miles I adjusted the cable twice to take up stretch. It seems to have stabilized now with an additional hundred miles on the clock, but I'm still in that vary paranoid phase of putting a full resto on the road. Should I be worried about this cable?

I have had clutch nuts that were possessed and would unwind from the end of the cable a little at a time. Make sure you have a new nut, 11mm, it has a delrin insert to make it lock a bit. Never reuse the nut. Carry a spare nut.

Maybe measure from the end of the nut to the end of the cable to see if this is your problem instead of a stretching impending failure cable.

Paul

I have always double nutted clutch cables to keep this from happening

Can be a road side repair. Always carry a spare clutch and throttle cable. Two fail points that ruin a drive really quick.

Clutch tube security check is to have someone operate the clutch while another person observes the movement (if any) of the end of the tube where it exits the firewall. It usually breaks the attachment here first, then fatigues the attachment to the tunnel wall ahead of the gear-shift.

Cables can stretch, but usually not a great deal. Great changes in adjustment usually are the failed tube.

Actually the shortest ground if your strap isn't working (or missing from the transmission to body) is the clutch cable.

I suspect that is where your issue lies.

I got the privilege of driving without a clutch in the Dalles WCR.

It will heat up and stretch. Other than that the cables do not stretch any appreciable amount.