I'm sure you've all seen the big Summer Sale that is happening in the Market right now (if you are able to log into your account, that is). There are lots of dragons and habitats on sale. Many of the habitats say "now upgradeable!" I went around my islands and found that many habitats I already own are now able to be upgraded to hold 5 dragons, so at least S8 answered one of our requests! Be sure to check for habitats that you can upgrade to get more dragons on your islands even if you have expanded to all of your available plots or have reached your habitat limit.