As I see it Beta construction was a phantastic way to get high torsional stiffness. It has always been the biggest problem of all new shaped skis and the main reason some earlier designs, eg. Snowrider in Austria, did not succeed.
The downside, at least in race skis, seemed to be the flex. While the big guys were strong enough to bend the skis the ladies have always been fighting with stiff Atomic planks. A prominent example was Martina Ertl when she left Volkl and joined Atomic. The early Beta Race 9.28 is said to be the least tolerant and most demanding Beta race ski. The current trend toward soft (at least in GS, cf. the Atomic philosophy with soft shovel and tail) favors sandwich constructions.
Interestingly enough, the flex has never been an issue in non-race skis, already the first Beta 9.38 from 1996 was a nice ski and the 9.18 became a legend. Fact is that the original Beta got some modifications quite early in lower-end skis.
I don´t want to write the Beta off. Regardless of its future it served its purpose and became the heart of some of the best and most fascinating skis in history.
Btw, the principle of a profiled cap filled with some core material is by far not dead. The real cap, say Monocock or Monoblock, should have cut production costs and made skis cheaper (cf. also the Volant story). Afaik, there was some cooperation between Volant and Head resulting in Head´s FMJ, Full Metall Jacket. While Head still uses a variety of jackets (fibre, carbon, titanium, liquidmetal) their new Superframe Technology featuring "a stable outer frame" and "a lightweight core material" "inseparably connected together" almost looks like a new chapter in the old book.
Another story is the fact that Beta is patent pending (Elan knows well from the time they introduced the X-Press arms...). Otherwise there could be others using that principle as well.
I´m sure that Beta will always have its share when remembering the shaped-ski revolution and the resulting changes in ski racing.