Some of them for sure! It's so much easier for me personally to just tell the currently-preferred-LLM-model or agent to do something for me instead of dealing with apps and dashboards!

Some will, some won't. I prefer some webapps to their native ones and vice versa. I used to run some proprietary apps that I replaced with open source ones, often clients interfacing with already self hosted stuff. I rarely touch Kagi anymore because my own hosted model + searxng drops results faster. I don't expect most of these apps to go away just because of agents/assistants alone.

Proprietary apps and services will probably go into protectionism and will shed users in doing so.

Custom launchers and widgets will likely be replaced by user instruction-driven processes at some point.