This decision will most definitely impact hotels' digital marketing strategies, especially those which do not currently include the Google Ads Suite. One notable consequence is that tracking social media campaigns (among others with the Facebook pixel) will become very difficult and might incentivize hotels to move away from this kind of marketing.
To add some context: 42.7% of internet users worldwide (16-64 years old) use ad-blocking tools at least once a month (source: Hootsuite). When Google announced their intention to stop third-party cooking tracking on its Chrome browser by 2022, other browsers like Safari and Firefox already made that change years ago.
There is two parts to the problem: a) how does a hotel ensure that their ads now hit the right target and b) as you rightly said, how is the tracking going to work at a hotel level but more specifically - how are vendors currently tracking that data will change their mechanism, if at all required?Whilst its nothing new that google just gatecrashes parties and owns verticals once broken into (with travel being a major one i believe going forward) I find it highly interesting that google goes back to "segmentation" whilst always playing the "hyper personalization" card in all other areas.On the other hand - how do most hotels really use that information anyhow?