It's not hard depending on what you want to do. I mean, think about it... Say you work a day job, 8-5 or so. if you're home by 6pmish, you're done with dinner by 7, 7:30.Even if you want hit the sack around 11 to get up at 6:30... that's 3-4 hours of free time each night. You can easily play a bit here and there. I used to come home and while dinner was heating up (this is winter, so I often had stew or roast chicken etc), I'd do some emissary stuff. After dinner, play an hour or so if I want.
The harder part is maintaining a strict schedule. Sometimes you might get home and just not WANT to sit in the game for 3 hours but you're signed up for a raid. That's why I no longer raid but just LFR it to see the story and get a few upgrades.
It also really depends on what else you do during the week. If you want to go out, chill with the BF/GF, etc that takes evenings. So, yeah, you might not play as much or as ambitiously but you can certainly play.