how can the offense NOT take a step back?

I don't think anybody is arguing that Brees doesn't need some talent around him to succeed. The team has always found some standouts and then plugged-in role players.

A foundation of Colston, Cooks, Spiller, Ingram, and Watson looks like a solid starting point at the skill positions and then the consideration becomes whether some of the more unknown/unproven players are ready to step up.

There are certainly question marks but the cupboard isn't bare of talent.

We all know that Payton's offense is predicated on creating mismatches. Spiller, when healthy (like Jimmy) is every bit the mismatch that Graham is. Colston transitioned from Option #1 -> #2 when Jimmy broke out, and now he is moving to Option #3 behind Cooks and Spiller. The Saints are really trying to find that #4 option who is going to see 60 targets. Could be Watson, Hill, Coleman, Jones, Snead, we aren't sure yet.

But, history shows us that the Saints will move the ball down the field.