How about reserving one index for XCP so you won’t need to add XCP to the LUT table?
One could also give, say top 10 assets based on number of sends, their own hard coded indexes too?
Furthermore, a range of indexes can be left open so that in the future the most active assets at the time get their own reserved indexes too.
Once an index is granted it should never be revoked, so lots of indexes will be taken up by (eventually) dead assets.