Salt Lake City is the 124th largest city in the US for population and the 66th as far as size. Portland a more walkable bikeable city is larger in size and population, so size isn't an issue. If there is a will there is a way.
The next argument I though could come up was how Salt Lake City is in the mountains and hilly. Denver, Colorado is #5 for most bikeable cities and is arguably more mountainous or at least equal to Salt Lake City.
We have a good transit systems and are ranked #22 in the nation for that, which helps us become a city primed and ready for bikes! There are some hills in the city, but there are not only ways to negate the hills, but maybe a little cardio would do us some good.
I two sister-in-laws who have three children, and I think about them when I try and imagine a city based on public transportation, walking, and biking. The thing is you have to imagine the people that will use the space you are trying to develop or plan. If you fail to take thought of all who use the space when developing a plan, your plan will most definitely fail.
I put myself in the shoes of those trying to use the space. For this example I will be in the shoes of my sister-in-laws specifically.
Grocery shopping and taking your kids around, how will that work? These are the questions that have always stumped me in the above type of design. At least I was stumped until I saw this video:
Would this work during the winter? Maybe not as well, but that is where public transportation comes in. Am I saying all of this will work today, with the culture we have? Honestly, not really because it will take a giant culture change in the US for this to become extremely successful. It is possible though. Once people see this as the cool or popular thing, that also saves them money and puts them in better health, it will still take developing the habits and the infrastructure to make it stick.
As I said before it is possible, as there are already solutions to every question one could potentially ask. Are all those solutions best suited for our needs? I think with a little creativity, community involvement and brilliant design and marketing we could make it work within the next 10 years. You might not think this realistic but I don't. Our generation has a crisis of the imagination, and it isn't because we don't have fantastic imaginations. It is because we don't use them.
In 10 years time we could make massive culture shifts, as we have already done it. 10 years ago, how many people owned cell phones or computers? Think what kind of culture shift that had. So I say again it is possible but it is going to take all of us to do it.
This kind of shift would bring economy back into balance as we wouldn't need to spend that $20K for a car, then spend another $1K - $2K on gas and oil changes per year. That isn't even taking into account tires, windshields, and other things that go wrong with the car. Talk about a lot of unneeded debt!
If it was not only safe to ride bikes and walk people could use the money to improve their homes, have a change of clothes, and for some...eat. This would drastically bring our social circles closer together and help to rid our country of the horrid economic gap we now experience. Imagine cycling in Salt Lake City, it's not out of our grasp!