Data sticks around for a lot longer than “a long time”.
Which is why it's nice that current-Apple is committed to not collecting data.
My comment was the work Apple would need to do before collecting that data. Anyways, GDPR gives you the right to deletion at any time. Apple has publicly committed to offering GDPR rights to everyone.
However, for a company like Apple to change its stance would take a long time. Culture is sticky and, furthermore, they simply don't have the mass data collection and processing pipelines necessary for such an about face. There would be a fairly long period (my guess is years) during which consumers would be able to change providers.