Already in some countries in Europe a classic is prohibited from motorways and is limited to a few thousand km a year. This could happen hers, in the guise of "road safety and pollution".
Peter can you be more specific on this? I know about some cities restricting old cars from the city centre but if there is a country prohibiting my Morgan from motorways I would like to know which it is before I get in to trouble. As for restricting the number of miles driven in a year, I think that depends on whether you choose to register it as historic or pay for normal registration. In Austria for example my Morgan (and most cars over 30 years old) can be registered as "historic." This gives you cheap insurance and limits you to driving on 52 days in the year. But this is voluntary, not compulsory. One can choose normal registration and suffer no restrictions.