Agreed, it's important to keep relevant, and to learn new languages, technologies, etc. Many of the new tools, just re-invent old solutions with incremental improvements. For most businesses, it's just not worth the cost to jump to something new. Also, the risk-adverse nature of high availability environments dictates an attitude of measured and careful change.
Your clarification on staying relevant makes your initial statement clearer.
In the end, most of us will be working with technology long out of date, because it pays, and occasionally with technology that is new, because we want too.
Average developers will continue using Java as forward-thinking engineers use Scala, JavaScript, and other progressive languages to solve real problems faster.
Employed developers will continue to use Java, COBOL, Pascal, or whatever their employer's code-base is written in. This seldom has anything to do with the skill of the developer, and almost everything to do with the cost of converting functional, stable code to a new language. The case to move to a new language must include benefits in excess of the stability of the existing code-base.
Average developers will make a mess of any code-base, regardless of the "new hotness" status of the language.
3.) There really are not all that many Blackberry users out there versus Exchange users (or even Domino users)
In any problem, if you find yourself doing an infinite amount of work, the answer may be obtained by inspection.