Even if the channel is completely empty, it will still stay open (see screenshot below from my Phoenix wallet's channel list). I have been using Phoenix since September of last year and been very happy with it; it's a solid non-custodial wallet, in my humble opinion.

P.S. @DarthCoin I know you catch a lot of crap on here for your strong "opinions" on various LN related-issues, but I wanted to say thanks for taking the time and patience to educate folks not as far along as you on the LN path to victory. Cheers, friend.