I don't think they would do that unless Lemmy continues to grow to a point where it challenges Reddit. Then it becomes a technical issue. I don't think they can do that. It was one thing for threads to do it, being designed with that in mind from day 1, but it's completely different for Reddit to do it. There are so many features that just wouldn't make the jump, and so much content that would need to be reworked.
If they were going to do it, it would most likely be a clean break where you just can't access old Reddit content on Lemmy, but all their new stuff would be accessible.
I also just don't see them giving away their content like that after cracking down on the API how they did.
Because we have to defend democracy or it will be eroded. We should not stand by idly as misinformation and corporate interests continue to cripple it. Just because people are voting against their best interests does not mean they are no longer their best interests.