Possibly no one? Still have Aurier and Walker Peters. The former is yet to find find any consistency in two seasons at Spurs, not helped by injury. The latter needs to start playing. If he can’t break through this season, then he needs to move on for the sake of his career.
A third option is Juan Foyth, who did a decent job at right back for Spurs on a few occasions last season and equally so for Argentina in the Copa America.
Would be a gamble not to buy a replacement - although Tripps had a poor season so won’t be greatly missed - but it may be a gamble worth taking if it allows KWP to fulfil his potential.