Short term big maybe...Long term No....Used cars will go up due to continued delays in manufacturing of new cars. I dont even think Toyota the number 1 manufacturer are hitting their usual 10.5 million cars per annum atm...its reduced by 1 million. Increased demand for used cars equals higher costs.
That trend will continue up to and beyond 2030. So you're probably in the wrong camp. Prices will be at their peak in the next 5-10 years. To the point of unattainable.
There are collectors, sunday drivers and people out there that would still want them. It only takes Car Wow or someone to review it again for the sheep to start buying. Driving prices back up.
Just because Genghis Khan is going to expand ULEZ, increase VED, add noise cameras and toll roads rendering driving expensive along with other city mayors doesn't mean these cars wont be sort after. Keep that in mind. Only takes a day for a few to come off sale.
EV are going to be hit by road tax VED or road tolls. Eventually congestion charge post 2025.