Investors should be careful about assuming that demand for artificial intelligence products and services will remain high for the foreseeable future.There could be signs of trouble looming ahead for the markets. While the economy is still doing relatively well and tech companies are reporting strong numbers, the danger is that in the not-too-distant future, there could be some weakness. And I'm not referring to just the possibility of a recession.Spending on artificial intelligence (AI) has helped many tech ...