I checked the official maps from ArDOT for Craigshead County.
Noted in clear text on the map was "End of I-555" at the intersection with US-49N (Stadium Blvd.)
Google Maps has it ending at AR-91 (Dan Ave.) based on the AASHTO letter.
I am still researching it locally.
I don't want to wonder off into fictional too far, but one response was that I-555 would go west at County-114 and hit the future I-57 via Winesburg. That it wouldn't go to Walnut Ridge-Hoxie at all, and replace AR-226 as the Jonesboro feeder from the west. That surprised me somewhat because I assumed they would just extend it up to the NW and over CO-114 (Gainesville Road) and bring it back somewhere near Bono.
Supposedly, this is why I-555 "ends" at US-49, (instead of AR-91) that they don't intend to keep it aligned to US-63 in the future.
It's all speculative for now, but it is interesting that the ArDOT shows it different than everyone else.