I wouldn't say that AI is killing B2B SaaS, let's analyze the situation: AI is shifting the boundaries of the Build VS Buy decision.
If software is cheaper... building it seems a much better option but... ...the fact that software is cheaper means that SaaS companies will be able to be more competitive with price, offering more features, integrating them much better with the newest agentic tools and frameworks that are getting released.
Sure, the market will adjust, some will be pushed away, others will find businesses that weren't possible before... but we're far away (I hope) from the AGI revolution, don't forget to see this crysis as an opportunity too.