Yes, they can win the Series for the first time in over a century because they are one of the best teams in baseball. It would make no sense to write them off simply because of their history. This current team is good enough to go all the way and might do so.
Yes, the Cubs can win the World Series. This might finally be the year the Cubs reverse the curse. They have the best pitching in baseball, and their hitting isn't too bad either. If they want to win the World Series, they'll just have to get the the Nationals in the NL and the Red Sox in the AL. I think they are good enough, though.
Even if a century has elapsed since the last win, it's possible that the Cubs can seal the deal this year, particularly because they are playing well and have established a winning rhythm. Provided they continue to play at their peak potential, they are just as likely to come out on top.
Really I'm sure it's a possibility, but I'm a Cardinals fan, so I can't really root for the Cubs. Objectively speaking; they did win the NL central, which is their first title since 2008, they're on pace to win 104 games (as sad as that makes me), they have a huge run differential, and there's no one else as dominant right now. Their bullpen is good and has post season experience, so yes it's possible.