I have felt for a while that Twitter is really a horrible way of creating an online community. It seems to me it’s mostly for individuals with a high follow account to get their message out but for the rest of us looking for community it’s a waste of time. Reddit on the other hand I think it’s very good, we follow topics and reward valuable posts without caring who posted it.
I will point out that Mastodon and Pixelfed are Federated and open source versions of Twitter and Instagram respectively. Although, I do remember seeing something about Pixelfed's founder stepping away for a while.
Alternatives for many things already exist. Only thing missing for many is large enough userbase. We can't trust every company to shoot themselves into foot like reddit did nor can we trust they will do it thoroughly enough. We can build what we have into inherently better services than what corporations have.
We probably can't recreate all the bells and whistles as the corporations have made, but actual freedom to do what we want, be it creating content or improving the services itself, is worth more than anything those moneygrubbing shits can create.
I don’t think the user base needs to hit the size of Reddit. It just needs to reach a size of critical mass where discussions are productive. I for one have not unsubscribe from Reddit, but I have killed my paid account and will promote the use of Lemmy, wherever possible, mostly by posting and participating in the groups I’m interested in.
Mastodon in particular had a big boom after the whole deal with Musk. It's more popular than Lemmy still.
Open source TikTok is a different deal, uploading videos takes a lot of storage space. Plus it's hard to imagine TikTok really taking off without the profit motivations behind it.