With just standard desktop or laptop, is it possible to mine obscure altcoins in the hope that one of them will take off?
Yes, it is possible. Most altcoins are setup with low enough difficulty that you can CPU or GPU mine them, like you could with Bitcoin in the early days. However there are so many of these small obscure altcoins and almost all of them are just useless clones of some other coin or pump and dump scams, so you are likely going to just end up wasting electricity.