One lesson we should take away from the "death of the mainframe" talk is that we often get so excited about what's new and shiny that we forget the ecosystem and experience that surrounds what that new shiny thing is supposed to replace. We forget that, regardless of our excitement, we really, really don't like to change. We tend to forget that "better" is relative. Finally, we have a nasty habit of getting so excited about a new technology that we ignore the fact that it fundamentally doesn't work for us.Sun Microsystems, for example, led the vanguard of the firms declaring, "The mainframe is dead." Well, Sun has been gone for about a decade, while the mainframe remains IBM's most successful hardware platform from the standpoint of revenue and profit.Let's talk about the never-ending death of the mainframe. As long as it evolves, it's likely immortal \u2014 and this has implications for the impending death of the PC.Mainframes' Massive I\/O Enable Survival of the FittestThe mainframe remains relevant for two reasons: There's a ton of software that didn't migrate well to any other architecture, and there's the mainframe's massive input\/output.It isn't that other architectures couldn't match a mainframe's IO \u2014 I recall a successful effort by Microsoft to replace mainframes with then-Windows NT servers in the late 1990s. However, the CIO at the time candidly said that, had he paid for the solution, he could've bought three mainframes for the same cost.\n[ The Mainframe Turns 50: IBM System\/360 Launch Was Dawn of Enterprise IT ]\n[ More: Mainframer Remembers 'A Fantastic Time to Be an Engineer' ]This was often the problem (or the benefit) of the mainframe: At a given high I\/O load, the mainframe was the most cost effective. This made them ideal for database implementations. But the mainframe did need to evolve \u2014 and back in the 1980s, when it was declared dead, it very nearly was because it hadn't evolved.This has changed in the following decades. Today's mainframe runs current-generation platforms, uses cutting-edge hardware architecture and includes power and cooling solutions that are often a generation (or more) ahead of the high-volume market because it's a relatively low-volume product and can more readily accept those enhancements.Now, the mainframe isn't for everything; newer architectures perform better for tasks that lend themselves to a ground-up solution, such as hosting and rendering. That said, firms such as BMC provide compelling mainframe tools. While the mainframe clearly isn't the center of the digital universe any more, the platform still carries some of the most critical data center tasks of the enterprise.The PC, Like the Mainframe, Won't Go Extinct Without a FightSome vendors still trying to claim that the mainframe is dead \u2014 but, Sun, the loudest, is gone, showcasing that it's been more economically viable to support the mainframe than stridently scream that it's dead.To that end, a lot of folks scream that the PC is dead. If it doesn't evolve, it will die. But it is evolving. This week, AMD is saying desktop sales are surging while tablet and smartphone sales appear to be stalling.\n[ News: HP Reverses Decline in PC Sales, Claims Broad Progress in Quarter ]\n[ Analysis: Desktop PC 'Killers' of Past, Present and Future ]There are two reasons for this: Desktop PCs are evolving into smaller, appliance-like products, and tablet and smartphone users are finding they need a desktop, not a notebook, when they get back to the office. They just want an all-in-one device or small form factor appliance, not the obsolete PC tower.Why not a laptop? These devices are attempting to evolve, but the display hampers its capability to defend against the encroachment of tablets. What's fascinating is that we pretty much declared the Windows Tablet a failed experiment a decade ago; even Steve Jobs thought tablets were stupid, and he's the guy responsible for the current tablet wave.It's also fascinating that a lot of the folks I know, adamant that the tablet would replace the laptop, have shifted to using iPad Mini tablets and MacBook Airs for getting work done without admitting that replacing a laptop with a tablet was a stupid idea in the first place.Conservation Efforts Saved Mainframe, Can Save PCYes, many technologies that have gone extinct over the last five decades were incredibly popular in their day: Wang Computers, the bulletin boards, modems and Network Operating Systems (Netware). Each died because it didn't evolve \u2014 PDA vendors could have made smartphone, bulletin boards could have become content and social networking sites, and modems could have been network cards.The non-death of the mainframe showcases that even the most archaic of platforms can evolve and remain relevant if the folks who manage the platform act to evolve it. Here's to all the mainframe supporters who stepped up and assured the future of the mainframe. And here's to never forgetting an important lesson: Evolve or die.Rob Enderle is president and principal analyst of the Enderle Group. Previously, he was the Senior Research Fellow for Forrester Research and the Giga Information Group. Prior to that he worked for IBM and held positions in Internal Audit, Competitive Analysis, Marketing, Finance and Security. Currently, Enderle writes on emerging technology, security and Linux for a variety of publications and appears on national news TV shows that include CNBC, FOX, Bloomberg and NPR.Follow everything from CIO.com on Twitter @CIOonline, Facebook, Google + and LinkedIn.