Google's AppEngine has upgraded their Developer's Console and it includes a monitoring tool called Cloud Trace. Is this an improved version of the AppStats profiling tool? If so, can I remove the configuration files that were previously required, like appengine_config.py and the console path in app.yaml?
builtins:
- appstats: on
Cloud Trace is in beta, meaning "it's not covered by any SLA or deprecation policy and may be subject to backward-incompatible changes", while AppStats is a supported component of App Engine.
The implication, to me, is that you probably should not yet depend on Cloud Trace in production applications, but that it's an excellent idea to experiment with it in development versions -- if you use a lot of RPC traces/stats (a great way to keep your apps in fine shape!-), it's probably worth your while to experiment, both with using Cloud Trace on its own and with "doubling up" with both it and AppStats.
This way you will learn whether, in its current beta state, Cloud Trace supplies all the information you find relevant to tuning your apps' use of RPCs, as well as whether also having AppStats produces any change in Cloud Trace's functionality (per the docs, it shouldn't [*], but, beta does mean beta:-) in your apps (which is the most relevant to you:-).
[*] so to explicitly answer the Q "can I remove the configuration files that were previously required": the answer in theory is "yes!"; in practice, "it's beta, do try it in a development, not production, version, and see if it breaks" -- as for most any new feature in beta:-)
Having both on lets you compare and contrast the measurements they offer, checking if there's any systematic or random difference that could affect your use of said measurements (again, there shouldn't be, but, etc, etc:-).
Since AppStats is a supported component, it is subject to the usual deprecation policy, and thus it will be around for a minimum of one year after it's officially announced as deprecated (if such an announcement ever happens), so there is really no urgency for you to consider migrating production apps off it at this time.