This was Modric's best season in terms of assists too. Kroos usually did better, but half his assists came off set pieces
At the end of the day, from open play the Casemiro-Modric-Kroos midfield averaged like 15 assists a season between the 3 of them. I don't see that as something Camavinga and Tchou can't reach, particularly if we add another playmaker
I don't think its just about assist. Apart from far superior creativity, Modric and Kroos has been among elite passers in the game too.
In terms of passing stats:
Modric - 1.3 key pass, 58 pass (90%)
Kroos - 1.8 key pass, 77 pass (95%)
Camavinga - 0.5 key pass, 32 pass (90%)
Tchouameni - 0.6 key pass, 59 pass (86%)
Quite a big difference.
Real really need someone with creativity and good passing to play alongside these 2 in future, when Modric and Kroos retired.