And the 2 MB hard fork should contain also a restriction for legacy transactions. Maybe they can be prohibited and all people owning bitcoins on non-Segwit keys have to transfer them to Segwit addresses.
Can't do that.On an isolated network with full blockchain - do a soft fork. If it works then make multi copies of the blockchain. Required a huge degree of trusted parties. [..]
I don't really understand your proposal. Do you mean this for the case "legacy transactions are prohibited" there is a backup for non-upgraded nodes? Well, the idea was to "prohibit legacy transactions", not "prohibit legacy keys" - it would be
forever be possible to transfer them to Segwit keys - otherwise, many people would lose their Bitcoins. I think that's what AngryDwarf said here and is also what I meant (I perhaps wasn't precise enough):
I would consider it might be possible to make them eventually "send only" addresses after a grace period which allows users to change any known public receiving addresses.
I was concern about those who hold bitcoin but do not follow the news daily. Maybe those will ignore bitcoin and wait 10 years. What happens then when they find their bitcoin is "prohibited"?