What could Yared Nuguse do in a fast-paced 5000?

I could see him hanging with Katir honestly, your prediction seems reasonable

Katir is faster in the 1500m this year and did 5 seconds faster in the 3000m this winther. I really don't see why he should be able to hang with Katir in a 5000m.

Nuguse won that 7:28 race, while Katir lost his 7:24, and Nuguse has a better kick than Katir at 1500m. In time they are very close at 1500m. In any case, Nuguse would have run very close to the American record at 5000m, and I say he would have beaten it in Monaco with 12:44-45.

While this is reasonable it isn't the whole story.

Katir ran his 7:24 in a losing effort, basically pushed to the line. Nuguse won his 7:28 with a quick close. The 12:45 from Katir was quite "slow" & tactical between 3000 and 4400, too, so he might be able to run even faster. Krop kind of slowed it when he went to the front (I guess he was going for sub 12:40 but maxed out when he went to the front on this day).

Depending on how strong Nuguse is, I can see him going as quick as 7:22-24 and 12:40ish or as "slow" as 7:26-28 and 12:55ish. It really depends on how much resistance work he did going into outdoors. As he ran 3:29 I'd say even with his 7:28 3000 he should get a good bit under 13 in a well paced 5k as 13:00 is only 7:48 at 3k.

To put it the other way: I definitely see Nuguse as quicker in a 5k than Klecker. If he is able to go 12:40-45ish would have to be seen when he prepares a 5k and actually goes for it.