I'm basically in the same position as your friend.

Some are saying that guys like us are very well positioned since the industry will take about 1-1.5 years for hiring to resume. I figure that if I hold onto my day job and instruct in the evenings and on weekends it will take me a little over 1.5 years to get to 1500 hours.

Your friend should definitely get his CDL and a suggestion would be for him to flight instruct part-time after that. If it becomes clearer over time that the industry in indeed picking back up then he could switch to flight instructing full time to try to meet the next hiring wave as soon as he can.