I tried to do this once... it is pretty much impossible to predict but usually too fun to resist.
Here's what I think will happen:
On the surface things will look fairly similar. Density will be higher but most Americans (keeping this in the USA BTW...
) will live in single family houses, drive cars (on the ground, still no flying around), get their stuff from stores and work 9-5 jobs to pay for it all. On the whole people will be poorer than today but crime, pollution and illness will be SUBSTANTIALLY lower.
Cars will be electric. Batteries will last 3-400 miles and be capable of instant recharge faster than we can fill up a gas tank. They will use "self-healing" panels and finishes, be able to change color at the push of a button and all be self-drive capable.
Most cars will be rented on a per-use basis, not personally owned. When you want to go somewhere you will order one, it will drive to your doorstep and return to the rental garage by itself when you are done with it.
Work and Entertainment through direct brain interface will be very popular; you will be able to "live" in and experience virtual worlds that are indistinguishable from reality. Large numbers of people will retreat from the real world into the virtual, some on a full time basis while their bodies waste away in special care centers for years at a time. "The Matrix" movies will seem strangely prophetic in 2100.
There will be no wires or plugs; electricty will be sent though the air to appliances like a phone signal. Most power will come from large orbital solar power stations which catch solar energy without interruption and beam it back to earth.
There will be a technology backlash of sorts... many people will crave "real things", "real experiences" invisible tech and/or anachronistic things. Artistry and craftsman ship will make a strong reappearance... for those who can afford it.
Space travel will continue to lag; man will have made it to Mars and even the moons of Jupiter but manned space travel is still uncommon and not available for the masses. Unmanned probes will have been sent to the nearest star systems but will not be anywhere close to their destinations by 2100. There will be small scale lunar and Martian bases for scientific research but they are not self-sufficent.
Medical care will be amazing. It will be entirely possible... even easy to cure any disease we know of today. Pharmacutical drugs will not be used; they will be entirely replaced with nanotec cures which actually go after the problem directly on a cellular level.
But new (mostly psychological) ailments casued by virtual reality and direct brain interface will plague the people of 2100 no less than heart disease and cancer plague us.
Lifespans can be extended past 150 years... and any part of a body can be replaced with a grown part, including the entire body through a brain transplant. Genetic manipulation/replacement parts and cyborg implants will have effectively lead to several new transhuman species, though nobody will be willing to admit it yet.
Real A.I. will exist but will be on par in abilities to transhumans. The line between one or the other will blur; it will be hard to to tell and even irrelevant if a sentient being was born in a womb or on a quantum computer. Most A.I.s inhabit and feel comfortable in the ever expanding series of virtual worlds called the "net"; the evolved version of the internet but some will seek external experiences through cyborg bodies. To them, the "net" is the real world and the "real world" is the strange "other place" they go to for fun.
The net will be the reason crime is so low and people tolerate otherwise spartan lives; it will provide the ulitmate escape. Even the poorest person can connect to the net and set up a virtual space where they are near-gods. Governments will find it especially easy to keep the populace under their control and real-life warfare will be a rare event. But strife and worry between transhumans and homo-sapiens is increasing; purely biological Homo sapiens are doomed to complete extinction by 2200-2300.