Whatever it is, it won't be sold as an AI product. Coding and writing tools are probably the easiest to predict. An AI hiding in IntelliSense popping up and warning you that your lacking the proper exception handling, that you're leaking memory and offers to add the missing code, is already doable. Just don't label it as AI, it's realtime security screening for your code.
Or writing an article in Word or Google Docs, having a built in fact-checker akin to the spell/grammar checker is clearly useful. Pink squiggly line, your facts are incorrect, click to fix. Hell built that thing into Facebook or X. Again, it's not completely out of the question to add that right now and have it add the correct sources.
LLMs are clearly useful, but they aren't really a product, they are an engine you can put into other things.
Would be lovely, but many issues. 1. If LLMs can't reliably produce factual information today, how can they check if any statement is factual? 2. What about writing that is not recounting facts? e.g. fiction or marketing? 3. who decides what is factual? Does the system give a pass to statements like "full self-driving" or "AGI" or anything accompanied by "the likes of which have never been seen before"?