It really depends on the cats. During my student days I moved from a house with a gated backyard to an apt with with no balcony. My 2 cats were fine and had no problems. I leave the windows open (it had netting) and they used to sit there.

But I have a friend who lived in a 3-brm apt with balcony then moved to a 1-brm apt with a sliding door but no balcony. After a while her cat started to pee and poo everywhere, including in the bedroom. Then she had no choice but to lock the cat in the washing area while she's at work.