I really feel sad for the close down of Mandrill, although we are not affected as we are also paid MailChimp user, so we can merge our accounts. However, we are considering moving away MailChimp due to this, just don't like the way they do business.
We're in the same boat. It feels like Mandrill is a second class product to MailChimp. We've also started facing massive deliverability issues to some providers (like Hotmail and friends) that are proving very hard to correct.
We used constant contact and Mandrill at the small non profit I'm on the board at. This move basically killed the idea of moving to Mail Chimp. It was kinda a bait a switch. We use very low volume so be willing to pay a little, but moving to an fairly expensive plan for transactional isn't going to happen.
It looks to me like Mailchimp but not Mandrill are (for now) keeping their small-scale pay-as-you-go plans. But, they force you onto a larger plan if you try to merge your Mailchimp and Mandrill accounts. If I'm not misreading it, it's US$70 per month minimum -- too much for the nonprofit folks I serve.
So, I'm trying SendGrid for transactional messages and sticking with Mailchimp for onboarding emails (a sequence of messages sent a few days apart to new contacts with consent of course).
Sendgrid was seamless to adopt. We'll see about deliverability.
