Is it Too Late to Make my Outdoor Cat Indoor?

I have a black and white cat (cat in image on the left of my name) named Snowy. She used to be an in door-out door cat until just recently. She's been staying outside and I think it's because of my grandmothers dog who visits ever once-and-a-while. We just keep her food outside now. She's 4 years old (about) and I want to know if it's too late to make her enjoy being strictly indoors. I've noticed that indoor cats can stay by your side more often.