Well, just my opinions... IMO these particular questions are largely answered.

But I suppose the answer to the OP is 'yes.' Historical questions and questions about the future are sometimes impossible sort out (since it could require time-travel). It's probably physically impossible to answer some valid questions.

Edit: I would add though that questions that cannot be answered should be examined closely. They might not be valid questions if there's no methodolgy (even in theory) that would confirm or refute any particular answer. These questions are like asking "How many Zorks are in a Blorg?"