I am neither a newbie nor super experienced with Europe trains... but this is the least time I've ever had for a connection. We are going from Prague to Vienna. Should I be worried?

I purchased this ticket on Ceske Drahy following the instructions on seat61, and it is a connection ticket as sold by CD. However, isn't three minutes cutting it too close? I am especially antsy because the ticket has a section that says the connection (i.e., the train we are connecting to) is "obligatory" - does that mean that we are on the hook if the train from Prague is late, and we miss our connection? Or does the ticket permit us to take the next train should the train from Prague be late?

Of course, our best case scenario would be if the train via Breclav to Vienna is on the same track/platform - but when I looked at the google maps for Breclav, it appears that there are at least four platforms.