I would think that having "The Jim Clark Edition" might add a thousand or so but not much more. I work now as a classic car appraiser. My thought is: Is there going to be a collector car market in twenty to thirty years? I have serious doubts. The generation following us has some interest in cars but less than us and the generation following them appears to have none-that is a major concern if you think that buying a high priced classic car is going to be a good long term investment. Perhaps this isn't nostalgia but it certainly should be of concern to us!
I agree that city dwelling youngsters who are more tempted to fly somewhere for the weekend rather than go for a drive aren't going to develop an interest in old cars (or even new ones, many don't own cars) - and the way everything is being dumbed down (regulations as well as the cars themselves) means that driving will become less of a skill and even less pleasurable which is not going to increase the number of enthusiasts.
But there are youngsters who are interested in cars, racing and so on and you only have to look at the number of track days to see a glimmer of hope.
The future of old cars, steam trains etc has been discussed many times and the worry that young people don't remember the originals turned out to be unfounded - look at how popular the London to Brighton run is (and huge numbers of young entrants) and there are very few people around who remember seeing them in period.
As you say the idea that a high priced classic car is an investment is questionable - and now that houses are starting to sell again I think the slow down in affordable (e.g. those that cost similar amounts to current) cars will be pretty rapid.
But the really expensive stuff is different - people spending millions on cars (paintings or whatever) have plenty of money left over and the numbers who have that kind of money is increasing rapidly (these days we talk about the number of billionaires in the way that we used to talk about millionaires not so long ago), so, as with shares, as long as they can keep attracting new investors such investments are relatively safe.
As far as the original question goes, electronics (+ air bag type rubbish) has to be a problem long term, but as with the more recent F1 cars it turns out to be pretty cheap to replace an old ECU system with a much better current one so keeping them running will be possible, but keeping them original might be difficult.
But then how many computer controlled cars are going to appeal to enthusiasts in the future anyway - if I wanted a car that drives itself I'd get a taxi...
A Ferrari analyst has suggested that no recent Ferraris will ever be collectable since they make far too many of them, the same applies to Porsches, Astons etc - some very limited production cars will have some appeal, like a Lexus LFA if you can keep it running!
The upside of the huge production numbers is that there will be plenty of cars to break for spares so it will be possible to throw a bunch of second hand ECUs at a car in the hope of finding one that works.
Another analyst did suggest that one thing that will increase in the future is the popularity of automatic cars, given the current trend towards automatics many drivers in the future will have no experience of manual cars, so the 3.8 manual overdrive Mark 2 Jag might become less desirable than an automatic one!
Ultimately I agree that the Lotus Elise is one of the outstanding recent cars and will remain popular, similarly Honda S2000, MX5 is the modern MG Midget/MGB and Nissan Skylines, Evos & Scoobies are the dream cars of many youngsters and well enough catered for that they will be running for many years to come. But the huge numbers produced will limit their values.
BUT, the old cars that are popular today is clearly connected to the current company - Bugattis values increased when Audi stuck a Bugatti badge on something, Aston Martin values increased when Ford gave Aston the kiss of life, current BMWs are popular so the collectors have discovered an old BMW that is OK and consequently shot up in value. The Ferrari PR machine is so good that many otherwise sane people believe them to be the most important car company ever...
Lotus has never been a widely sought after name and their current sales aren't promising, so will they be around in the future and if they aren't that does not bode well for their values - not that they were ever likely to be huge.