OK... so where's its replacement?
We’re in the same situation as we were when Apollo was done and the Shuttle had not launched (1972 to 1981). It’s NOT a major problem. And this work is really better done by the private sector rather than the government (welfare for engineers is what we have now, and I worked in manned space flight [ground systems] for 6 years so I have some experience to calibrate on). Check out - http://www.spacex.com/ and http://www.scaled.com/ for what’s coming next. And in the not too distant future. Better, faster, cheaper.
We should have been working on a replacement for the last 30 years.