hmm... I like Kachanov a lot but I am afraid his not currently consistent enough to deal with Nadal (given his recent results), but I haven't seen him play so this is just a guess.
As you know I am not particularly impressed with Fedal's level in the last year, with a few exceptions, the last two matches of Dubai for example. Saw Federer playing Edmund today, it was quite good, but the scoreline of the first set was also due to Edmund's very slow start. Being fair to Federer, his stats were quite good, specially for an attacking game plan.
If Fedal do meet, I feel they both will raise considerably their levels, but I think this particular court will favor Federer, let alone the string of results.