What other options besides ifupdown are there for general users/sys-admin?

The two other main networking tools nowadays on Linux are Network Manager and systemd-networkd.

ifupdown isn't going away yet, the change in netbase is just cleanup: there's no reason for it to recommend networking tools (considering recommendations as defined in Debian Policy), and removing the recommendation is safe because default installations still end up with ifupdown installed. Cleaning such dependencies up will simplify possible future switches to other default tools.

You may use

sudo ifconfig eth0 down 
sudo ifconfig eth0 up

If you have wireless interface use

sudo ifconfig wlan0 down
sudo ifconfig wlan0 up