So what will really happen?
Its funny seeing some of the comments here, specifically those around "breaking the internet" and most can see that this information being public is more harmful than helpful (those that still "need" to access the data will be able to, just a bit slower).
But in reality what is likely to happen?
I foresee that ICANN will just implement a block/filter on showing the data on the service in the interim (easy option) with the ability to provide the information on receipt of a suitable request (legal). But then I expect the US players (media orgs in the main) to put pressure on the US gov to implement a law requiring the publication of the data (just like what was mentioned for companies house data in the UK) that would trump GDPR. This will be rushed through and then ICAAN will disable the filter (or give people the opportunity to relinquish domains).
That's my guess anyway - and as a result I see more fake information being recorded (making the whole thing pretty useless anyway).
If the data is kept private then there is more chance of people providing real information.
Would they prefer accurate data or public data - I don't think they will get both.