All products have life cycles.
Just as organisms are born, thrive, and eventually die, products also go through a similar cycle. However, it is reaching the end of its life cycle, and will be displaced by next generation technologies which do more, cost less, and are easier to administer. PBX vendors seem not to realize that they are not fighting a specific technology. If the problem were this simple, it would already be solved. It isn't that simple because several important technology shifts are occuring simultaneously.