Whilst I have little doubt Tate would like to return to the Broncos, there are a few problems there; first and foremost, he's getting on a bit and is somewhat injury prone to boot. Bringing in stopgap solutions instead of developing a player is a tricky art to master, and Griffin appears to be playing the long game- which he can afford to, given the results of last season and this so far. Secondly, he's lost a bit of pace and was always better in the centres than on the wing. If he were signed he would almost have to play in the centres given his stature in the game and paycheck, so Jack Reed would be squeezed outwards. This goes back to the long-term development point; Reed is good and will only get better, and that will greatly hamper his development as a player.
Ultimately I feel that we are still going to be well covered for wingers. Losing Gagai is a bit of a blow given the expectations around him, but no one player is irreplacable if you need to keep a club's culture and ethos strong. There are always young players coming through, and the wing is ideally suited to them; Griffin has shown a talent for identifying and developing such players and bringing them through to the first grade, so we don't need to be hitting the panic button just yet.
If worst comes to worst this year, Gillett will get a starting gig.