Old reddit users are last I checked in the Reddit traffic stats I had access to around 1-2% of active posters, and mobile overall is thumping desktop reddit several times over.

By the time New Reddit was launched old reddit wasn't even the primary way to view the site anymore. Nowadays new reddit crushes old reddit. Reddit doesn't need it's old users, it doesn't need you, and it doesn't need me. It could kill off old reddit today and it would be fine.