"Ask and you shall receive"....
As announced yesterday during the Elastic{ON} keynote, XPack is going to be fully open-sourced, so that definitely offers one other alternative to people/companies who must comply to GDPR and don't want/need to subscribe to XPack just for the sake of being GDPR compliant. I admit I didn't see that one coming, but it has the merit of also being fully in line with what I highlighted in my above post.
This move has most certainly been planned for quite some time, so let's just thank Elastic for being such a visionary company.