You can buy anything but it would be depends on the seller if they would accept cryptocurrency or bitcoin so far the things that can be bought by bitcoins that I know are listed below:

- Services (different services that offered by freelancers)
- Collectibles
- Digital goods
- New investment / New Assets
- Sometimes Physical goods

so far here are things I know that can be bought by bitcoin plus the things that was listed on the articles you've given on your post.