Honestly, I think we are naive in thinking that GAI will just become another service. From our perspective it will be like inventing magic. Ask it what you want and it will give it to you.
The future will truly be stranger than fiction once GAI arrives. It will be like nothing we ever imagined.
Consider how buggy most software is. Consider that we have nothing approaching a general theory of computation. Consider that we cannot measure the quality of any given non-trivial piece of software. Consider that we don't even know what "quality" means in this context.
Consider there are minor mathematical issues - the halting problem, P != NP, the Incompleteness Theorems - which strongly suggest that all possible symbolic systems must be either incomplete or lacking rigour.
Consider that the thinking around AI is an unholy mess of millenarianism, techno-evangelism, philosophical confusion between unrelated concepts (learning, personality, emotional drives, sentience, self-improvement, general intelligence, "magical" post-human physics...) and wishful thinking.
I'm completely happy that we can build AIs for specific domains that perform better in those domains than humans do - because we already have.
I'm fairly sure we can build learning machines that can analyse a domain and provide a practically useful overview of it to a much deeper and broader extent than we do already.
I'm also fairly sure that process has practical and mathematical limits which are analogous to the transistor size limit for Moore's Law, and that the nature of symbolic computation itself makes it the most difficult of all domains to master.
My guess is there won't ever be a post-singularity god-AI. But there will be AIs that appear smarter than all humans in specific areas. And that these AIs will continue to be dumb slave machines which do what we tell them to, because domain mastery is completely orthogonal to any requirement for sentience, personality, or motivation.
What if that area happens to be persuasion?
The singularity already happened, in meat space, i.e. Humans. Now those same humans are trying to create AI's smarter than themselves. We still have not accomplished it but we will. All of this looks self evident from my point of view.
Remember, people used to think that humans would never fly. But why would they think that? There was plenty of evidence that flight was possible. Evolution invented flight, then we did the same. Evolution invented GAI in meat space, now is our turn to do it. This is a virtual certainty, unless we destroy ourselves.
The singularity also happened in net space--the Internet.
For all of its faults, the Internet is really effective external species memory. All of our current AI relies on the Internet as its "storage".
A GAI will be smarter than the entire human race combined. It really does not matter how much computing power you have if it is not GAI.