Alternative writings

That depends entirely on the nature, power, and extent of the magic. If everyone can use it for every little thing (such as, for example, most all Dragaerans in Steven Brust's books) then of course they will, and will never bother with anything else! (which is, in fact, the case with said Dragaerans) On the other hand, if there's any sort of limitations, people will find other means to get what they want done. A good example of a hybrid sort of setting would be the Fullmetal Alchemist manga/anime series, in which "alchemy" can be used to do juuuust about anything, but there's a very strict price to be paid, and it takes research and knowledge to use it well in the first place. So a lot of people and places make considerable use of it, but they also have guns and cars and radios for all those little things that alchemy would be too much of a hassle to bother with. So it's very possible to do hybrid settings, it's just a matter of balance to make it work logically.