It's doubtful that more than 5 News Boards to choose from will ever be added to the TinyPortal code. In all the time that TinyPortal has been around, you are probably only about the 4th or 5th person that has asked for this. A while back, during an earlier version of TP, there were even less than 5 News Boards to choose from and it was increased to 5 a while back. Back during the coding of the early betas of TP 1.01 there was a method discussed for adding more Boards. In fact, I even made a post showing how to have 15 Boards though that method would not work with the latest TP.
It is possible that we would discuss this for a future version of TinyPortal, perhaps when TP gets to the 2.0 stage but certainly not before. That will be awhile before that happens. If you really need something like this now, your best bet would be the "Multi-Functional posts and topics snippet" located at this link --> http://www.tinyportal.net/index.php?topic=33026.0
You'd have to play with the configuration of it to increase the $bodylength to a number greater than zero (maybe 200 or so) and use it in probably an upper panel block, but that would let you show the topics from every board if it's set up right. However, be aware that we recently found an issue with the file used for that snippet for SMF 2.0 and it won't work properly with mode 2 until Freddy has updated the file.