Not sure how fast that will happen though. For Belgium it was mentioned in our news just this week that at the moment none of our F-16's are spare. Yes, they will be replaced by F-35's but those aren't here yet. Hell, Belgian pilots aren't scheduled to start training (in the US) with the first 8 Belgian F-35's until later this year and actual deployment in Belgium isn't planned until 2025. I don't know if the circumstances (Ukraine needing F-16's) might expedite that but this schedule is from november last year, so pretty recent.
The Netherlands are a few years ahead on that schedule and already have operational F-35's if I read it correctly so maybe some of their F-16's are available?