In the update videos posted on the Ladybird YouTube channel it's said that they have exhausted most of the low hanging fruit in terms of correctness. Browsers and the web standard have a very long tail of odd behavior that you need to implement. I could be wrong, but if I had to guess they'll stall at a point where it's just good enough that some people will make it work, but it's not really useful for general use.

Ladybird is extremely slow, it's far from being competitive at all.