No, HND is very much alive and thriving!
It's by far Japan's busiest airport and ranks just below LHR in the table of busiest airports. It handles mostly, though not exclusively, domestic traffic.
When the bulk of international services were moved to NRT, a handful remained at HND (GMP, SHA, TSA, etc.) but now that there are four runways, international services to/from HND are expanding, and limited flights to/from Europe and North America have recently restarted.
It's not hard to understand the continuing popularity of HND, it's dead convenient for Tokyo being just a short monorail ride away. Compare that to the trek all the way out to NRT.