I've read lots of people estimating what a loaded model 3 might go for and then have someone immediately say "for that price why wouldn't you just purchase a used S".
I think a loaded 3 might be better and here's why (just speculating but let me know what you think)
Model 3 vs used p90dl
Model 3 loaded:
600-800lbs lighter(just a guess based on size, materials, and improved cells reducing weight)
More nimble/better handling - could be moot based on suspension setup but most likely with lighter weight
Better cd - around 15% more aerodynamic
New cells - more efficient
And very, very likely more range - base will probably compete with bolt and highest battery option should deliver 30-40% higher kWh than base 3 (assuming 55 base and top pack around 70-80kwh)
Perhaps very close to as quick 0-60 - theoretically it could surpass a p90dl with cd, lower weight, and new battery efficiencies
Of course full warranty remaining is huge as well
Used Model s has a couple things going for it:
7 seat configuration if you have a larger family
More useful trunk
Supercharging for life (which could be really enticing for some)
I did make the assumption that Elon won't restrict the 3's performance just to make S customers happy or keep selling the S. personally I think tesla will put most of their model s focus into upgrading its interior quality.
This is also assuming the P90dl would be in the same ball park $ wise as a fully loaded 3 which here in Canada it's approx 95k USD for the cheapest p90dl used.
This is also assuming that used MS won't crash in price once the 3's final specs are released...a lot of ifs but let me know how crazy I am