So think of what body of text you want scanned and how you'll get that.
The algorithm that does the scanning and matching is already known, too, and there are many versions to choose from.
The second problem is computer hardware. You need lots of it and it has to be really fast, and that's prohibitively expensive. The same kind of text scanning and matching can be done on your own computer, but it will take a lot longer.
The last part, and the reason for "chat" in the name, is a polishing and tuning module that OpenAI put on the end. It's there to make the sentences more chatty and friendly and to have them all conform to a certain "house style" of speech. This secret sauce of theirs is very impressive but it also can be duplicated by others.
Already, many people are dreaming of, investing in, and building ways to commercialize the idea behind ChatGPT.
So, the answer to your question is that many alternatives to ChatGPT are already here and new ones will continue to come and go forever. Think of this as a basic type of tool like a hammer or spell-check that's here with us for good and will be incorporated into lots of things. Probably too many.
And that's only what has been made available to the public, there's many other models that are not available to the public. There's Google's LaMDA and others. Meta has invested heavily in AI as well, etc.