What counts as a 'true competitor'? You seem to be asking if there's a chance that someone will upend Google at search, and Facebook at social networking. But

What counts as a 'true competitor'? You seem to be asking if there's a chance that someone will upend Google at search, and Facebook at social networking. But that's not how these companies pay the bills. They built massive ecosystems around their original businesses, and they use that ecosystem to mine data and serve ads. With this money, they've amassed social and infrastructure capital, so they can out-build competitors (Google Drive, Docs), branch out into other product lines (Google Cloud Services), or simply buy them out (Instagram, WhatsApp). To compete against them, you need differentiation and feature that appeal to a passionate audience. Snapchat, for example, attracts people who've seen or heard how damaging it can be to publically post on Facebook. DuckDuckGo appeals to people who don't want trails of their web searches making it into ads they see on websites. Dropbox works for people because they put out a solid product and aren't trying to force you to be part of a large, monolithic ecosystem. But it's an uphill battle. Facebook's preferred strategy is to buy out services before they become dangerous (they tried to buy Snapchat back when it was still known mostly for sexting), and Google's is to outbuild others. They form a very effective duopoly in a way.