I see what you're saying now. I never had that much of a problem with magic items in AD&D 2E, but I did tend to play more than DM. Admittedly when I first DM'd I gave out those books that increased stats to a bunch of level four adventures so maybe I didn't have a good feel for items.

Even still, I'm not entirely sure that the game is going to be broken by magic items at high levels. If the starter set is any indication wands seem to be usable by anybody that cares to pick them up, and other items set a particular function of a character to point X (for example: boots of striding and spring set speed to 30 feet per round and add a bonus to how far the character can jump). If most items follow this style, then I don't think it will be that big of a deal.
Well, I agree, it remains to be seen.
If it is in the form of items though, that's a whole lot easier to control since the game's math doesn't assume magic items to be functional.
That's both true and completely false!
On a simple level, it's true that it's very easy to control in that if you know or suspect that an item is trouble, you can prevent PCs getting it, because as they aren't working into the system, there will never be an assumption that they can get it on the part of the system (unlike 3E, fr'ex).
On a more complex level, it's completely false, because when magic items aren't assumed to be functional, and there aren't clear guidelines on how powerful they should be, nor clear indications of how powerful they are, but rather they just exist independently of all that (as in 2E), then it's much easier for a DM to think any item is fine, or that it will be harmless, and to then find that the PCs have come up with a really cunning plan to leverage it in some outrageous way (ironically enough, it's rarely plus-based magic items like weapons/armour which are the issue, normally utility oriented ones, or easily recharged or infinite charge use-based items). The amount of trouble a Portable Hole, for example, caused me as a DM in 2E (mostly fun stuff but not all of it!) was pretty huge.
Indeed, thinking back to 2E, think of the most optimized and overpowered PCs, the trouble they caused absolutely PALED in comparison to the trouble clever PCs with magic items caused. If we're talking time wasted looking up rules, arguing over how things worked, or adventures entirely derailed, I can think of zero examples from "optimized PCs" (in D&D - and excluding high-level Mages - games like Cyberpunk 2020 are different matter entirely), even though I dealt with some serious ones, but soooooo maaaaany from magic items!
So hence my suspicion. We shall see though!