AFAIK it was more of a conceptual study rather than a fully formulated, finalised plan as the 2nd Tianhe was meant as a backup. But since the first deployment went swimmingly, now they're sitting on an extra core module with no more service modules slated to be built other than the current two under construction right now.
Who knows, maybe with further international participation (e.g. UNOOSA, Italy, France, Austria etc.) and perhaps even external funding as a result, an enlargement to the current config could be justified. It's certainly feasible at the very least.