The idea yes, the execution not really. I didnt like the strict this way or that way approach, hybrid multiclassing, and the saves are just whatever your good stats are approach of 4E. More akin to 3E/PF1 where you had wholesale multiclassing, archetypes, and particularly feats that really opened things up (but without the optimization gap).
I'm not a big fan of free for all muticlassing myself.
But I don’t think we need to debate the entirety of 4e here so let’s just focus on the ‘Primary+Variable secondary’ aspect.
The Rogue would pick a Rogue tactic, in this case the Artful Dodger or Brutal Scoundrel Option. An Artful Dodger gets +CHA to AC against opportunity attacks and a Brutal Scoundrel adds STR to their Sneak Attack damage. Then, later on, some powers have an extra if you have the specific Rogue Tactic.
For exemple: the Rogue’s Encounter 1 ‘Fox’ Gambit’ includes an effect that lets the Rogue shift 1 square (i.e. move with no opportunity attacks), but an Artful Dodger can shift a number of squares equal to their DEX mod! Sometimes the bonus involves CHA, sometimes not.
Most basic 4e classes are built like this. There are a few oddballs in the PHB1 that instead have two possible primary but that model was dropped by the time of PHB2. Clearly, an Artful Dodger and a Brutal Scoundrel don’t have the same powers that are optimal, nor the same incentive to pick the same skills.
We probably don’t specifically need to tie down those extra effects to a chosen Rogue Tactic and instead just have stuff that you can pick with a bonus from CHA, some a bonus from STR and some without any mod related bonus. Maybe later you add an option for INT bonus, etc.