The content already is better!
Depends where you go. For instance, the discussions in AskLemmy seem better than the discussions in AskReddit right now, but lots of communities are basically empty still. The main baseball community on Lemmy.ml only has a few highlight videos posted, pretty much all from the same user. The corresponding Reddit feed would be much more active with both posts and highlights. It’ll take a bit of time before enough people migrate over to start posting content again.
Probably 2 to 5 years. Lemmy kinda just works and is usable right now. To become better than Reddit the experience needs to be seamless.
I would say reddit’s golden years were around 2012. Since it started around 2005 that gave it 7 years to get as good as it was in 2012. If Lemmy follows the same formula, it may take about the same amount of time, but reddit saw exponential growth when Dig shot itself in the foot, much like reddit is currently doing, so it’s possible we may get a jump start. Who’s to say really?
I say a year. Lemmy itself still has lots of UI issues to sort out and smooth over before “it just works” for someone trying to pull-up an instance, join, and find the right communities they want right away.
Probably 5 years. I expect to see a lot of content be reposted from reddit over the next years. Mostly stories and informative posts.
Highly dependent on the status of reddit. If after a few days most subreddits return to normal status, whether willingly or forced by admins, or that users just create new ones to replace them, then I believe most users will go back to reddit and leaving lemmy as where it is.
But if Reddit truly dies, then lemmy will become very big and active in no time.