LLMs do not guarantee either of those, so unless they improve to the point where they do, this really doesn't change the overall market, it just changes the level of resources required to play.
What LLMs are going to replace is more likely to be the spreadsheets that departments run on, sharepoint and salesforce lists, and other such low-cost, low-effort, and legacy tools that departments tend to use for their own local processes.
Some of this can be automated. We’ve seen the result with the big companies though.
Anyone can spin up a SaaS now, but knowing what information actually matters to a specific audience is still hard to replicate. That's domain expertise, not technical skill.
I think the value is shifting from "can you build it" to "can you filter the noise." The bottleneck isn't access to information anymore - it's attention.
So large software platforms, think Jira/Confluence, MS Teams, SAP etc are not affected. But AI will definitely eat the solo dev SaaS, especially those handling trivial use cases.
At some point AI platforms will struggle to monetize at the model API layer due to local models catching up. This is why the model providers are focused on AI model integrations at the application layer which invades traditional SaaS companies.
You now need to think very carefully about 'what' to build and assume that someone with a AI agent can clone your SaaS and race you to $0 as a risk.