The show needs less 20 somethings and more a mix of cast. I think this creates a nice balance and then an injection of life and story narrative into the show. Some examples:
Roo and Marilyn can be given a love interest with a teen - Its not that hard! Justin lacks a friend of his age and he is grouped with Lyrik or Alf and John. Bring in a current 20 somethings father in that case
Reduce the sibling squads. We've had Rose/Xander (Jasmine really didn't last long with them), Tane/Ari, Cash/Felicity, Dana/Harper, Levi/Eden/Abigail, Mack/Dean in the last 3 years.
More Nuclear families: The Astonis are sorely missed in my eyes (Bring back Ava or utilise Theo/Leah/Justin better)
No more river boys: They just aren't the same
Interwine old and new: Bring back some old cast and not recent departures, I am talking like Sally, Alfs family and make sure the actors they cast/recast want that recurring balance. It'll give current characters purpose.
Adam below has also said some stuff I think needs to occur (in bold and underlined)
I can't say Ive watched the show this year and I find it pretty boring