A few things:
1. Over time more DJs will step into the arena of offering "MORE STUFF" in attempt to maximize income. That also means that as more, and more DJs go this route, and appear to offer the same thing (Totems with Moving Heads, Photo Booth, Up Lighting, Nice looking Facade, Club style mixed music, step and repeat etc. etc.) It will also become harder to "Stand out" among these "Event DJs"
...That means that over time, the prices will also likely decline, or stagnate at best for what the "Event DJ" can charge in their market.
2. There will always be BUDGET CLIENTS. EVERYWHERE. Especially in Rural Areas. Actually, in rural areas, it is unlikely that the Event DJ will be prominent. There might be only 1 guy who ends up going this route in the whole market, and the budgets will be generally too low to really support that one guy's business.
3. There will always be "Mobile DJs" who charge far less, and show up with a single sound system, and maybe a small light show to do gigs for $200 to $700. They will always be around. Also, the clientelle to support these DJs will always be there. Perhaps less clientele in the future, but these guys will still get gigs. Meanwhile over time, other DJs who buy into more stuff to offer will have a tougher time getting premium dollar as more and more DJs go this route and competition grows. DJs could find themselves offering everything under the sun for $1.500 to $2,500 when 10 to 15 years prior, a quality Wedding DJ COULD have booked weddings for the same prices without any Up Lighting, PB, totems with moving heads, and all the other stuff.
It will be the way the cookie crumbles so to speak.