Firstly, assets service and inventory service are two completely different services. Inventory, for all practical purposes, is a link to one or more assets, in combination with permissions flags, object type, etc. Inventory is the object you encounter in the virtual world; the asset(s) are the Real World (tm) digital artifacts that decorate your virtual objects.
To be precise:
The asset service cluster has some issue that causes a deadlock of sorts, preventing ROBUST (the asset service software) from starting. This is not unusual; though the nature of the issue is. Typically, OSgrid staff are in a position to deal with asset service cluster issues. In this case, there was no prior experience with the issue so staff does not have a ready recipe for resolution.
The primary architect of the asset services cluster, Melanie Thielker, is suitably equipped to deal with the issue, and from what I understand, has seen it before. So it would not be unusual for her to fix it, at least as compared to those who generally address such issues. This is why it is said that the assets are not in danger; they are simply unavailable until such time as the cluster member deadlock has been resolved.
Unfortunately for the case of urgency, Melanie is tied up in RL with moving house. I've been told about 18 hrs ago that she'll be available to address the issue in 24-48 hrs.
So the tl;dr is, hurry up and wait if you wish, but patience will be less tedious; the assets are fine, Mel just needs to get the children to behave, so to speak.
Keep Calm and Soldier On, technical difficulties will be addressed effectively in the near term