Is there a clear equivalent of 'show keyspaces' in cqlsh 2?

Very simple. Just enter this command in your cqlsh shell and enjoy

 select * from system.schema_keyspaces;

In C*3.x, we can simply use

 describe keyspaces

Just try this:

describe keyspaces


However you may need specs of approximately the following (rather than those mentioned by yourself Crowie)

[cqlsh 4.1.1 | Cassandra 2.0.6 | CQL spec 3.1.1 | Thrift protocol 19.39.0]