Quick take: Prices for domains ending in .org will be going up over the next several years. If you have such a domain we recommend that you purchase as many years on it now as you can.
The full version: There are multiple companies globally that administers the domain name system we use to connect to websites, send emails, etc. The company that currently manages .org has announced that they will (potentially/probably) raise prices on .org domain names and renewals.
Currently, they are only talking about 10%/year increases, or $1/year. However, there is nothing that prohibits them from raising the fees higher or faster than that.
The critical thing to remember if you renew now for a long time, such as 10 years, is to use an email address that you will still have access to and use in 10 years for when the domain renewal reminders come in! We manage domains for all of our customers precisely to avoid domain names from accidentally lapsing, resulting in downed emails and websites.