This discussion has gotten so far from the original question, I'm tempted to avoid it altogether. But, my big mouth is forcing me to put in my 2 cents...
Based on my own experiences with Cliff, I would suggest the following:
1. Cliff never conspired with James or anyone else to remove Lars from the band. It was not in his personality. If Cliff did not like your playing, he would say it to your face. Lars did a lot of marketing to get Metallica off the ground. Cliff appreciated that, and was happy with the albums they made together (Kill 'em All, Ride the Lightening and Master of Puppets). The band was on its way up. Cliff was happy to be part of it. No way he was about to rock that boat. I think this is simply ridiculous.
2. I also think its in terribly bad taste to ask what if Kirk and Cliff had not switched bunks or what if Kirk had died instead? Fate happened. Kirk lives. And, he is one of the nicest, humblest lead guitarists I have ever met. Don't pile on the guilt he feels about that night. Its not fair to him.
Now, as for what bass Cliff would play were he alive today, I offer these thoughts....
I do not think he would play any of the Fender variants (Fender/Sadowsky/Lakland/Ernie Ball) as he always marched to his own drummer. Cliff liked the unusual and being different from the masses. There were plenty of guitar shops in the Bay Area filled with P basses and Jazz basses when we were growing up. Cliff never gravitated to those places. He would not want a bass like everyone else. He would want something that was somewhat unique and individual to him. He would also want a bass with powerful pickups and a heavy voice. I'm thinking the following:
-- Based on his love of Skynyrd and Leon Wilkeson, I think Cliff would have experimented with Thunderbirds/Fenderbirds. I think he would have dug the body shape and the sound of the Gibson humbuckers.
-- Based on his love of fishing, I think he and Les Claypool would have become close friends. From that, I would bet that Cliff would have acquired at least one Carl Thompson bass. But, given the cost of those basses, I do not think he would have toured with it.
-- Finally, I think Cliff would have continued to live in Northern California and that he would have been approached by all of the local bass builders with endorsement deals. From those, I could see Cliff gravitating toward either Modulus or Zon. He would have dug the carbon fiber necks and the strength of those basses. My guess is, had Cliff lived, the current "Flea" bass might very well have been the "Cliff" bass. -- No disrespect to Flea, he is a fine player and most-deserving of a signature bass. But, Cliff was first. Had Modulus signed a deal with Cliff, its very possible that they would not have continued looking for another big name endorser.
Anyway, thats what I think. Sorry for the rant.