I don't think you'll have a problem at all, especially if you get a puppy. They're so tiny and, from the cat's perspective, non-threatening (ha!) that the cat won't mind it.
Be sure to have an area in the house that is "cats only". Start off before you get the pup, making that area special to the cat, whether it be playing with toys or getting brushed. That way, when puppy does show up, the cat knows if it wants to "escape", that spot in the house is all his/hers. Also, be sure to continue the attention in that spot, as well as around the house.
With my cat (that story is a whole different ballgame), I made sure that Cooper (the dog) knew OmaKitty was in charge from day one. He's not allowed near her food, near her bed, near anything of hers. She doesn't like Cooper at all but at least he leaves her belongings alone.
We had cats my entire life and our chis always loved them and the cats, for the most part, loved playing with the chis. Cooper would love to play with Oma but she's got issues of her own and she just won't.
