There is definately a shortage of engineers, technicians and mechanics coming up. It has been on the cards and talked about for years. The airlines know this. This is why they have pressured the CAA/JAR/EASA into the A and B licenses. Work that was previously carried out by mechs/tech and signed for by A,C ad X licensed engineers, which added another level of safety as an "independant" inspection was carried out before certifying, is now completed by A, B1 or B2 people mostly working alone (on the line at least). This reduces the numbers of staff considerably but also in some ways removes another level of safety.
As mentioned earlier the average age of maintenance staff in the UK is relatively higher than say 10/20 years ago with most airlines not running apprenticeships so the youngsters don't get a chance to join the industry even if they really want to.
As for the argument of A&P versus B1/B2, i hold both A&P and part 66 B1/B2. There are pros and cons to both. The practical exam for the A and P is an excellent idea and not as easy as most people think. The part 66 theory exams on the other hand go completely over the top (in fact my module 5 digital techniques was more in depth on fibre optics than what BT engineers go through!) and could do with being updated to real world aircraft and maintenance techniques. The A and P theory exams on the other hand are relatively easier compared with part66 modules (helped by the answers being published) and not going into anywhere near the depth of part 66, but then a lot of what's in part66 which is irrelevant to day to day maintenance... when was the last time someone opened up a VHF transceiver to check the superhet IF on the line??
The problem with the A and P is that you are a "jack of all trades and master of none" as there's no differentiation between electrics/avionics/engines and structures There are very few people who feel comfortable with all these disciplines, myself included, as there's always a natural tendency to drift towards either the mechanical or electrical trades. Unfortuately the FAA don't address this problem and it seems EASA are drifting towards this way of certifying, again under the pressure of airlines to help fire fight the lack of trained mechs/techs/engineers.
Having worked with many A and P engineers over the years in the US they could seemlessly certify to EASA part66 standards but obviously but that is only my experience!
The days of 100's of apprentices being trained are long gone.