I saw the line up for the new 'United Cup' mixed tournament in Australia, (taking over from the ATP cup, I'm guessing). The teams are based on rankings and there is a huge mismatch of players involved. Serbia haven't qualified 
But- Norway have- despite basically being a one man team.
Rafa is down to play (no Alcaraz/ RBA/ADF) . Some teams obviously have more strength on the men's side and some , on the women's. And there are doubles specialists. So it should be interesting. GB seem to have a junior player making up their numbers (though I think the players involved may change in some of the teams).
I haven't really kept up with the Davis Cup- the format keeps changing, and the website is rubbish 