I honestly view this as a longer term play by the NRL. They weren't trying to overlap the Broncos area too much, they said that many times. The Dolphins will represent an area that is a growth corridor north of the city. It is possible that the Jets or Firehawks (maybe a merge) will come in, in the future and represent the growth corridor west of the city.
I think this is the NRL learning the lessons from Sydney. As we all acknowledge, there are probably not going to be any of the current Sydney clubs removed from the NRL so the next best option is to spread them to growth areas... Tigers to Campbeltown, Dragons south to Wollongong, Manly to spread to wider north sydney and the central coast. The NRL is trying to give the different regions of SEQ representation without overlapping too much and without oversaturating. Dolphins (North), Broncos (Central), Jets/Firehawks (West) and Titans (South) is a good spread will put a lot of pressure on other codes as it essentially locks in RL as the number 1 code forever.