When the 2021 games were awarded they were ranked 10th and 12th, and it probably wasn’t considered more than a mathematical possibility that they could actually drop out of the World Group.
Latvia were a pretty comfortable 5th in Group B and only just missed out on a Quarter-Final spot, so t’ll be a major shock if they get drawn in to a relegation battle in 2020. The possibility of Belarus being in a relegation scrap will probably hurt the chances of any of the smaller nations applying to host the tournament in future though.
Bottom line seems to be that you need to target a Top 12 finish and anything less than 2 regulation wins per tournament makes for a very uncertain future. 2 pts this year was good enough for 13th place, so it’s certainly possible GB could survive with only 1 win...