Unfortunately lots of them were lost back in 50s and 60s with advent of seed companies. Also in Europe selling seeds of non approved varietals is not possible. Legislation is changing slowly, but a lot of diversity is lost forever.

What you can see a lot on current market are "heirloom" varietals made by entrepreneurs that take industrial variatel, cross them to create new completely new varietals. But just because something doesn't look like modern tomato it doesn't mean it taste good.

You can still find old varietals in seed banks and around seed savers, but hip breeders are much more noisy in the market. I am not saying those new breeds are worthless, but they are kinda hit and miss and I would not consider them heirloom.