Note there's a pretty big difference between "it should be good enough for 99.99% of planes" and "we can guarantee there won't be even one crash even under unlikely conditions".
Aerospace is already VERY comfy doing ADS-B at 1090 and DME/TACAN from 960-1215 and the old GPS L1 allocation at 1575.42 and the military L2 allocation at 1227.60 (admittedly not many civies using that LOL) and someday probably L4 and remember ASR-11 airport radars blast at 25 KW power over 2700-2900 MHz. But, you know, the straw that broke the camels back and all that.
Most things will be fine. A small amount of things will operate degraded, which is the point of the NOTAM. Some things (like very few) will all fail the same time 5G is deployed, which will be a headache. Going forward every installation of every device on the ground or in the plane will be tested against 5G and it'll be just fine. Most likely for a week or a month everyone will have to treat their radar altimeter as potentially broken until proven otherwise, then it'll be fine and they'll drop the notam. Some equipment will indeed fail and connectors will be tightened or even devices replaced, and it'll be fine.