FWIW, there are many libraries out there that use the mp_ prefix. For example, ctaocrypt, a library with big number primitives used for cryptography and SSL implementation from CyaSSL/WolfSSL dedicated to embedded targets. A quick search on Google shows that mp_ is used in many libraries.

On embedded targets, especially with static linking, this creates name collision at link time.
Maybe it would be worth using a less common prefix, such as mpy_?

It is likely that micropython becomes highly popular as it deserves to. Linking with other 3rd party libraries - hence collision occurences would grow.