  We perform a detailed dynamical analysis of various cosmological scenarios in
extended (varying-mass) nonlinear massive gravity. Due to the enhanced freedom
in choosing the involved free functions, this cosmological paradigm allows for
a huge variety of solutions that can attract the universe at late times,
comparing to scalar-field cosmology or usual nonlinear massive gravity. Amongst
others, it accepts quintessence, phantom, or cosmological-constant-like
late-time solutions, which moreover can alleviate the coincidence problem.
These features seem to be general and non-sensitive to the imposed ansantzes
and model parameters, and thus extended nonlinear massive gravity can be a good
candidate for the description of nature.
