Hobbies are not dying, people today have more hobby choices than ever before. What is
changing is that traditional craft hobbies are declining in popularity when measured against other leisure choices out there
There are more people buying and flying radio control flying "things" than at any point in hobby history. I suspect that Hobbico failed to capitalize on two massive shifts in their core market:
1) The massive popularity of multicopter drones. Their current offerings look cheap compared to the 800-lb. gorilla in that space, DJI.
2) Horizon Hobby kicked Hobbico's ass on the shift from analog radio control systems to 2.4GHz systems. I don't know how it is where you live, but I see ten Spektrum (Horizon) RC systems for every one Futaba or Tower (Hobbico) RC system I see in the wild. My local HobbyTown store doesn't even sell Futaba products any more.
I further suspect that Estes is relatively healthy, and one of the bright spots in the Hobbico portfolio of brands. The core of their business is sales to youth groups and schools, and that is probably a healthy cash generator (sales types refer to this as "annuity business"), making Estes ripe for sale.
EDIT: If Hobbico slips beneath the waves, a LOT of local hobby shops will be negatively impacted. Look for mass closings in that event.