No. As long as people keep using it I think it can grow enough that people can use Lemmy as their primary app. But it'll never become mainstream enough.
We underestimate how technically ignorant the majority of people are, as soon as it hits the point of no official app and which instance to join people give up.
The only way I can see it working is it they prioritised their own official instance, made it default on an 'official' app so it's just as easy as Reddit or Twitter, but in small text allow people to change instance.
If you automate the right parts, its possible to go mainstream. I mean, remember what a hassle it was to get on the internet 20 years ago? You had to get a provider, get a card for your pc…so many roadblocks got removed and it went mainstream