The Jays definitely need to sign a front of rotation arm (Bieber, Woodruff, or Cease) + would be nice to bring back someone like Scherzer for a one-year deal. With both of them already being here, and if they've enjoyed their time in Toronto, probably gives the Jays an advantage and heads up over other teams.
Gausman, Berrios and Lauer are fine for the back of the rotation. Anyone of those guys could pitch like a No. 3 in the rotation. Gausman seems to be losing a bit each year like you said, so tough counting on him as a No. 1/2 guy like before. Berrios falls in the same category now. Lauer is a wildcard, but he showed promise this season so doesn't hurt to roll with him again.
Jays have a lot of depth behind those guys with Francis, Manoah, Macko, Bloss, Estrada, Schultz, Lucas, Yesavage which is a good thing over the course of 162 games.