I really doubt google will become "irrelevant" anytime soon. What most of us nerds forget is that tech products become popular when they solve real life issues for non technical people. We can sit here and debate all day what protocols are better, and which browse is cooler, and why Google is evil, because it will not become irrelevant anytime soon unless there is a better end user product. Happy bashing Google, Face…
Most of the end users today never made a conscious choice about this, in the same way most people didn't question Windows as "the operating system" years ago. Google is pre-configured almost everywhere, its brand name is synonymous with web search and most people never even try anything else. IOW, it's not the superior quality of the end product that decides the market share today, it's sufficient quality and no good reason to switch.