I have a 3-year membership. Is it still valid? What will happen when it expires?

Yes, absolutely. These changes are about what will happen after your existing membership expires. Your next renewal is guaranteed at the existing one-year Premium price, USD 95. As a 3-year member, you won't have an automatic renewal. When you get closer to your renewal date, you will be able to renew at the existing one-year Premium price (USD 95). Your renewal price is guaranteed as long as you don't let your membership lapse. If you're a Founder, you can renew at any time, even today!