The thing is, you're not losing your email client. You paid for Sparrow, the email client, as it was at a given point. If you were happy with your purchase a week ago, you should still be happy with your purchase. You still have the same email client you paid for, you weren't paying for future features.
This acquisition does not mean they're pulling your license to use the application, it does not mean they're disabling or hobbling the application, it simply means they aren't developing more features for it--only bug fixes and maintenance.
This acquisition does not mean they're pulling your license to use the application, it does not mean they're disabling or hobbling the application, it simply means they aren't developing more features for it--only bug fixes and maintenance.