I am unable to get the assets page layout as a feed-based layout, is it possible that feed-based layout is limited to certain objects? I can't seem to find this limitation within the help documentation.
the salesforce help for Feed based Layout Overview says
Feed-based layouts are available on account, contact, lead, opportunity, and custom objects.
So i believe its available only for the 4 standard objects and for custom objects. Any other standard object other than the 4 listed above might not have feed based layout.
additional reference : Creating Feed Based Layout
You can create feed-based layouts for account, contact, lead, opportunity, and custom objects. To create feed-based layouts for cases, use Case Feed.