For buying and selling things I will still use Reddit subs due to their size (PC hardware, watches, EDC items, etc). For general discussion, I'm heading back to specific forums and will definitely give Lemmy a go.
I don't think Reddit will die. This is a rough time. Reddit will survive. They will IPO, make some money, piss some people off, and once the dust settles things will go back to normal. Eventually something else will surpass it.
I'm not going to lie, I'm addicted to Reddit. While I'm not going to abandon Lemmy, I can't just leave Reddit. There are subs that can't be replaced. r/USMC is an amazing place to help active duty and veterans alike. r/Nascar has race threads that are fun as hell to read through. I'm going to limit my use to those subs that I can't get in Lemmy. (yet...)
There's no going back to normal if they kill the apps and maybe the old layout too.
I'm going to do my part to help Reddit become irrelevant. There's only two or three subreddits that I care about, and I never really participate there, it's more to get memes and news from my country. I'm planning to delete my 12 year old account with thousands of posts and just lurk in those subs and steal the content once or twice a week.
Delete your old post