I've used trail runners in snowy conditions. I stayed dried with the help of gaiters, the only problem is insulation. Can you keep moving with thick socks to keep your toes and feet warm? I recommend gaiters for sure, but then it's just matter how cold it is to keep feet and toes warm. If your trail runners can keep moisture out, i say go for it. Change your socks every so often as possible. I think it your feet will feel wet when it's not because of all the snow pressing on the materials. If you plan being ankle deep in snow it might be safer to wear boots. If you're on top of hard packed snow I say keep wearing trail runners, but i hike in different climate in the U.S. than you encounter in Sweden. So, in giving you a long-answer :), do a trial run locally by dipping your feet in snow locally with trail runners before you embark on the hike-if it's possible?