SHORT ANSWER:
Yes, your 1.x app will still work with OpenGL ES 2.0 Android devices.
DETAILS TO CONSIDER:
OpenGL ES 1.0 and 1.1 - This API specification is supported by Android 1.0 and higher.
OpenGL ES 2.0 - This API specification is supported by Android 2.2 (API level 8) and higher.
OpenGL ES 3.0 - This API specification is supported by Android 4.3 (API level 18) and higher.
There is cycle of development for OpenGL that allows OpenGL ES 1.x to be maintained but who knows for how long. OpenGL ES 2.0 came out in 2007 and then last year OpenGL ES 3.0 released publicly. OpenGL ES 1.x is going to die soon.
This graph of usage might be of interest for you:

From this you should see that only 0.2% of Androids support version 1.1 only and everything else uses 2.0 & 1.1. I would start using 2.0 if you plan on long time support of you OpenGL Application.
For more information about selecting the right OpenGL for your development, I would suggest reading "Choosing an OpenGL API Version";