Regarding self-driving vehicles (autonomous vehicles - AVs) I don't think it's hype, and there is a huge weight of economic logic and competitive industrial impetus. But it depends what you mean by 'mainstream'.
AVs will have to be able to share the road with human-controlled vehicles, for the foreseeable future. Initially it seems very likely that AVs will be confined to delimited areas, starting with cities and intercity routes, although those areas will steadily expand. That process could be pretty quick actually - think how quickly mobile phone networks expanded.
The question of how many conventional vehicles will remain will depend I think on how much cheaper it ends up being to use AVs compared to conventional vehicles. Note I say 'use' rather than 'own': most commentators are expecting that AVs will be much more like driverless taxis - ie you call up and use one when you need it. The number of people owning their own vehicle will steadily fall until it becomes a small minority who keep one.
Once AVs are an option, at least for some journeys, I think there's bound to be an acceleration in the number of young people who don't bother to learn to drive. They will just use a combination of pooled AV services and conventional public transport. In the UK we have already seen a very significant drop in young people taking driving tests, attributed to a number of factors including the increasing shift to living in cities and also the increasing costs of learning and insurance.
Conventional human-driven campervans and MHs will eventually, become the preserve of well-heeled oldies. Actually, what am I saying... 'eventually'??