There is no doubt that the current pool of refs is aging and moving away from the game, as well as young people not wanting to become officials. That said, the biggest problem is the rapid growth of registered teams at the youth level. Town hockey never went away, but all the "elite" "premier" "AAA""Select" programs added a second or third team (mostly filled out with players who also play for their town teams). This has created an environment where there are thousands of youth games every weekend, never mind juniors, college and high school (in a couple weeks).
I have been a coach, referee and hockey parent for over 20 years, and have had the opportunity to officiate college for the last 10. I have tried to encourage both my teenage son and daughter to referee and after a couple of years of going to seminars and doing some games, they now have no interest. Its really too bad more kids don't do it because there is no other place where a kid in high school or college can make $30-$50 an hour, get a workout and meet some good people.
When it comes to older officials, an even younger ones who have been exposed to higher levels of hockey, USA Hockey is the problem. They make it so time consuming to become an official. An all day seminar and 10-15 hours of online modules is enough to scare guys away from doing youth games. There is no incentive to being a Level 3 or 4 ref and despite there only being rule changes every 4 years, you still need to pay your $80-$100 and meet all the requirements i previously mentioned.
In the end it is the USA hockey, rink owners, programs owners who start extra teams and out of control parents and coaches who are responsible for the lack of referees or good officiating. And that is not to say that there aren't bad referee's but when you are screaming at a a young official in a squirt or peewee game because they missed a call then you have most likely contributed to a game going uncovered the next weekend or a lesser official showing up next time around.