There are already many "serious upstarts" that are doing just fine but will never reach the status of Google, like duckduckgo, bing, etc.
Some even say bing has better search quality than google. But that's not what matters. No matter how good the product is, if you can't get distribution it doesn't matter. Also, even if you do have distribution, it may not be the right context so it won't be effective.
If anyone is trying to really build a search engine to compete directly against Google, I can only say good luck, and prepare to be the most patient person on earth, because it won't happen fast, and probably won't even happen. Instead, while you're slowly making progress day by day with small traffic increase, you'll see some random new thing come out that had no intention of becoming a "search engine" (just like Youtube) and "disrupt" Google.
I have seen a lot of people talk about "disrupting something", and also have seen a lot of people who actually have disrupted their industry. The former are just wannabes, and the latter never said anything about "disrupting" something. They just saw an opportunity and went for it. And it ended up disrupting. Hope this makes sense.
p.s.
Google doesn't operate on the original pagerank anymore, there are tons of other things going on underneath. Also they now own many innovative AND popular "search UI" both through acquisitions and their R&D. Google Maps owns a lot of the map space, Youtube owns the video search space, and so on. Look deeper and you'll find even more that you've been taking for granted.