Space astrometry in the Gaia era and beyond

In this contribution I provide some thoughts on the options for future space astrometry missions, with a focus on global astrometry. The next big step in space astrometry ideally would open up a new accuracy or wavelength domain (or a combination of both), although a future repeat of the Gaia mission is an option that should seriously be considered. I outline the scientific and technical challenges on the way to global sub-μas astrometry, and make some basic recommendations for achieving this goal