What tech can you imagine that would make the conversion of electricity into thought 'no longer useful'?

This is an interesting question that I haven't thought about, thanks.

What we currently have is a simulacrum of thought - albeit a good one.

Any technology is useful only in the sense that it helps us with solving the problems we are dealing with in that time. When we face issues that a pseudo-thought is not useful in tackling or worse is one of the causes - this will recede in the background.

Beyond that, the implicit assumption in the question is that thinking is the highest form of activity that is useful to us.

I don't know how my thoughts arise but thinking happens when I engage with them. I think what we look for is meaning in our lives and thinking helps us generate/achieve one, whether real or illusory.