No. Mainframe is not dead, nor is it dying. To the surprise of all, it is coming back with a new look. It is resurrecting. This article and there are many such essays evangelizing the come-back of Mainframes. Only problem with mainframes (when viewed from programmer’s perspective) is that they are not very docile for the application development. But when viewed from a CIO’s eyes, Mainframes are around 80% cheaper than distributed systems (Total Cost of Ownership) and at the same time very efficient to handle heavy workloads.
It’s true that organizations are trying to modernize their old business critical applications. And in doing so, many of the antique applications are getting re-written into distributed platforms. IBM is investing a lot of time and money in reforming the Mainframes and has already done a lot to bring z series. New AD tools are being developed to ease the application development on Mainframes. One thing to keep in mind here is that applications developed easily might not be the best applications developed.
Meanwhile, change is around the corner. Truth is 'old and weak perish and new and strong survive'. Mainframe is old, but it's strong and has a bright future. But there will be changes in its core working style, which hopefully, will be for the good. As a wild guess, there will be new cocktail architectures – Mainframes and Java, Mainframes and Linux, Mainframes and Eclipse etc. Now, it is up to Mainframe professionals to align their career path with the changing Mainframe environment if they plan to thrive along with the changing times.