What makes you think NASA can develop a program for a sustainable presence on the Moon in 30 years given the performance over the last 30? Developing a program capable of sustaining people on Mars for 1.5 years in an environment with key resources readily available is far more progress than NASA has made in the past 30 years towards colonizing space. It would be a giant stride toward self sustaining colonization, while the incremental approach on the Moon is just as likely to be a boondoggle as the ISS because incremental gains that only slowly approach significant accomplishments are subject to public boredom and accusations of waste not to mention whimsical changes in direction. You need many huge advances including radical reductions in launch costs to make the Moon a viable colony. Send just a few missions to Mars to develop agriculure and insitu resource techniques along with conducting fundamental research in astrobiology and planetary evolution and one way missions are likely to be viable even at today's launch costs or at least the order of magnitude lower Musk is shooting for.

Mars could be a second basket within 30 years, but not the Moon. It's even reasonable to believe Mars could be an abode for unsheltered plant lfe within 100 years. Something that will not be the case on the Moon in the foreseeable future.

The simple truth is aim for Mars and the Moon becomes easy. Aim for the Moon and you ask for history to repeat itself with cancellation due to a lack of interest with minimal engineering advancement to meet "easy" goals. Develope the technology to get to Mars and it will enable commercialization of near Earth space which in turn will likely lead to tourism to LEO and the Moon giving us a two pronged path to a sustainable presence in space. Incrementally shooting for the latter risks financial and emotional fatigue which could easily result in failure to overcome the many barriers to a long term presence in space. Bold and determined has accomplished great things, slow and safe has been a dismal failure.

Regards,
Mark