Ask HN: How to do responsive design with 1080p mobile phones?

With devices cramping more and more screen resolution into small sizes, bootstrap and other frameworks won't scale anymore. (My understanding is they change layout based on resolution?)

Is there a good database of useragents mapped to screen sizes or some other way to know what type of device this is/how big the screen actually is in inch?

Obviously this will also be needed for TV designs for the possibility of different UX.

Any ideas?