If they did that, Reddit would just be an aggregator app of the Fediverse with different communities acting as a new subreddit. The difference would be that they'd have ads and algorithms.
On the Fediverse side, it'd be like having a lemmy.ml with 1000x the traffic and activity. We probably have to defederate to keep up with the traffic and the trolling.
On the plus side, 3rd party apps will be back baybee!
Be warned, take out/ delivery on NYE usually takes 1-2 hours longer if you're in the city. Lots of cancellations too. It might ruin your evening.