Email already connects everyone on the Internet but billions of people are not online by an accident of geography and birth. Mobile phones connect a reasonable percentage of the rest. I may be mistaken but it is doubtful that many users' quality of life would be dramatically affected by the sudden demise of Facebook. It may be as bad as losing your favourite TV channel, but life goes on. Facebook is a convenience that does not solve any of our real problems or alleviate human drudgery in any way, It only increases the enjoyment of existing wealth at idle time.
Incidentally, an explicit statement of what mankind's actual goals are and what resources are being committed to solving them would go a long way to show that we really all want the same things. Anyone that believes our interests are best served by large corporations and governments at war is delusional. These entities rely on the premise that success can only come at the expense of the 'other guy'. In the grand scheme of things they are local optima that promote the very scarcity that they have evolved to manage. Open Source Software can teach something here, there are multiple distributions and programs, each freely borrowing from the successes and avoiding the failures of the other. The healthy but open competition between them means that we get the best operating systems that no money can buy. Even OSS is not immune to meaningless rivalries and sabotage.
The information age gives us new tools to approach the physical world which is where ALL the real challenges still are, even in computing (think the end of Moore's law, and the potential of quantum computing and communication). You mention mechanical engineering, we should have amazing open-source mechanical modelling software that realistically simulates the physical properties of large systems, allowing you to design, build and test machines from a catalog of reuseable components and subsystems in a virtual lab (Tesla did this in his head), and send it out into the cloud for fabrication and delivery.
We all seem to agree that life is hard, why can't we approach it as an engineering problem? I would like to see someone attempt to engineer a society in a systematic scientific way. Evolutionary algorithms, game theory and a few Petaflops of modelling power for the common objective function. No secrecy, sentiment or ideology just let the best algorithms decide.