I say this because most of the old FORTRAN gurus are either dead or dying and there aren't many people out there to maintain legacy code.
You forgot there isn't also that much legacy code to be maintained. Fortran programmers don't make so much as best paid Java or C programmers working on top-level projects. There are very few chances you find an interesting project in Fortran. And maintaining legacy code is boring and usually low-paid. And there are no top-level Fortran projects...
Salary is much more dependent on your skills, experience and position than on particular programming language you mastered. By choosing a popular language, you just get more opportunities and wider spectrum of possible positions. You can get a quick and boring $30,000 job, but after some time, if you work hard and gain skill and experience, you can earn $150,000 on a top level project in some software company.
Referring back to the OP, I would say Python, MIT uses it in their introductory courses, it can be used in web dev, it supports many platforms, has many good libs and you can make your own built-in classes using c++/c.
In my field (aerospace) almost everything is still written in FORTRAN. Everyone knows it's dated, but I think people tolerate it because it's quite easy to create fast numerical code with it. Also, most of the existing NASA and aerodynamic codes are in FORTRAN, so it's just easier than rewriting everything.
I personally don't see the point when you've got c++, but since nothing in my field is written in either FORTRAN (for performance) and python (everything else) my skills in that field are totally useless. Point is, programming languages are tools, and being a "good" language doesn't help if you can't use it in the field...
Just thought I'd throw that out there to all the FORTRAN haters.
Here in finance, there's plenty of Fortran code too, even though all new development has been C++ for quite a few years. Our main application builds from 16 MLoC Fortran, 33 MLoC C, and 5 MLoC C++ at this point, so those skills aren't going to become worthless any time soon.