In order for magic to be supplanted, technology would have to supplant it outright in the ability to manipulate the local universe.
And it has to do so on every front, otherwise there's no reason you wouldn't just have magitech.
It gets particularly spurious an explanation if magic is just "um, not allowed" or "whoopsied"; that kind of thing was what they pulled with "the weave" on Toril, and basically is just *begging* to just blow back entirely with "AND THEN MAGIC BECOMES SUPREME AGAIN, SEE JUST HOW WORTHLESS S*%@ YOUR LASER USING CHARACTER BECOMES ONCE MORE" from a single adventure path or splatbook "unlocking" it back to full power. You definitely don't want that sword hanging over the setting's neck.
Conjuration will only be matched once you've got full-fledged replicators and transporters... except not even then, because one is the person themselves doing all of that and even calling in fully sentient entities, while the other requires massive amounts of reactor power, large machinery and computing, and often isn't even instant.
So the safest and most reasonable path is to have areas where science wins out a little, but a majority of areas (research-wise, not "places") where "magic" is no longer "magic", just a well understood part of the universe's physical laws. That little eternal flame inscription will last longer than an LED, that "fireball wand" is now fully rechargable (it's advanced enough we can build'em without that "burning out" problem), and with enough data that central computer 'augury' is far less likely to lie to you than any deity.
In other words; just like wizards first researched metamagic, thus applying "science" to their spells, technology continues to advance with full understanding that the 'metaphysical' stuff is nothing more than one of the many sets of laws they can exploit to achieve certain effects. After all, science is just the process, and technology is just advances. The first magic staves were a technological advancement, just, in a universe with "magic" in it is all.