Actually yes it would work, if the modem allows it... but it's going to be a bit of a hassle and won't work very well.

You might only be able to have one on at a time, which is more of a pain than just switching an ethernet cord back and forth.

USB for networking is just generally not a good idea.

I've seen people do it and there is mixed results. Some insist that it was perfect, most others say it's slower, unreliable and just a hassle to reconfig any time you have trouble with it.

Kinda like putting a b18c1 into a Corvette. Sure you could do it... but it's not a good idea.