Something to note; Board the Platforms and Race to the Finish were effectively combined in Melee(this is an opinion, to be clear). The 64 RttF was not based around learning how to make your character recover more efficiently. It was just a gauntlet/obstacle course at best. Melee's RttF however gave you enough time to show how fast you can get to an area, akin to what you try to do in the actual Board the Platforms.
That said, I think RttF(Melee or 64 style) should return and Break the Targets is best off being specific to a character, but I don't see how you could decently combine it with Race to the Finish. In both RttF and Board the Platforms, you're getting to specific platforms on time(or a door in RttF's cases), not trying to attack stuff overall. I think their overall concepts are impossible to combine effectively.
That said, more mini-games is nice, and I would rather try to stop combining mini-games, keep them separate, and let Classic Mode have lots of them(2 to 3 unique ones per go through) to keep the mode more interesting. Brawl's was a bit boring due to the Target Tests being the same for every character. There were no other unique mini-games, so it felt a bit more like a chore than a fun and unique mode. Albeit, 64's suffered from a similar thing, but at least the mini-games were different for every character(except Race to the Finish), so it somewhat worked better.
I still say keeping the general Target Tests is good for actual co-op, since it was very fun with two people, imo.