Registered Nurse is hardly a "niche" job and the fact that the US has a large shortage of them has not exactly been kept a secret. Yes, there are some that are "niche" jobs out there. If you are going to pursue a degree, then you should take the time to research the employment possiblities for that Degree. Before the market crashed and became depressed, there were jobs open for people who just had a degree, regardless of what that degree was in. In the current market, those employers who seek applicants are focusing more on degrees that have a meaning to them. There has also been a shift, amongst some employers, to a promote from within strategy instead of highering College graduates straight into management. This will mean that a larger number of graduates will not enter directly into jobs that are equivilant to their degree level. However, having a degree does offer greater advancement opportunities once hired and there is a ceiling on how high someone without a degree can rise. Anyone pursuing a non-speicialised degree, should now expect to enter the job market much closer to entry level employment than in the past. Even if the economy picks up, I suspect that many companies will continue with this pracice and we will continue to see the "underemployed" stats rise.
You mentioned teaching, we will always have a need for new teachers. There are several problems in that area which are suppressing the ability of those with teaching certificates to enter the market. With the economic downturn, states are forced into making cuts or have high deficits/debt. Education is one of the areas in which the states can cut. Unfortunately, they way the school systems are organised, at least in some states, is having a negative effect upon teachers. In Texas, the education budget was cut, however, the cuts were targeted towards reducing adminstrative positions, not teachers, but the way the structure is set up, those administrators are primarily the ones deciding what to cut, as a result, teachers keep getting cut while very few adminstrators get cut. The other main problem being seen by teachers is the inability of some districts to rid themselves of non-productive teachers who do not maintain required standards, however, there is strong opposition, especially in Union states, to basing teaching on performance instead of tenure and making it easier to get rid of bad teachers.
How much longer can we afford to let our human resources go to waste? Good question. Apparently the way things are currently going, we are going to find out. Even if we change Presidents (which I fervently support) and the makeup of Congress, I do not see a very fast or well thoughout turn around in America. I just do not believe that either party or any of the politicians available are going to do what will be necessary to completely turn things around. What needs doing will just be too unpopular for politians to do it. To me at least, it is not if we will eventually fail, it is a matter of how soon, and I see our current choices as choosing how fast we get to that point, not if we will get there.