>> Do we have any reason to keep the old endpoints available?
>
> Because if the user uses proxy for TD, changing default endpoint may cause the access problem.
Fair enough.

>> opts[:host] = @host.replace("api.treasuredata.com", "api-import.treasuredata.com")
>
> `sub`? Hm. `:host` option is not needed in almost cases.
> So I think keep existence behaviour is better.
But it is set and used for the import endpoint, through:
* import
** put
*** build_endpoint
isn't?