I have a customer looking exactly for the same increase, as a B2C business, they constantly increase associations between a custom object "store" and every customer. This is important for the B2C industry!
"We’ve increased the number of associations you can make between one object type to another from 10,000 to 50,000. For most object type pairs (e.g., contact and company), you will now be able to create more associations than ever before and leverage those associations across HubSpot...
You can continueto associate objects as you normally would(via API, import, or the HubSpot UI). The only difference is that with this update you’ll now be empowered to associate up to 50,000 records to a single object.
Please note that there are a small subset of association types that will not leverage the new association limit."