The idea behind declaring coins as "shalecoin" is to indicate whether an address has an holder or not and therefore to have an open and clean blockchain. (Concerning longterm UTXO)

- As mentioned before -
Definition of "shalecoin":
Coins with no access to the address. (Nobody has the privatekey)
If that address is a coinbase address: 1 year after mining
Other addresses: 10 years after last output transaction

Longterm holders of coins should transfer their coins to a new address within 10 years, so they wouldn't become shalecoins. All other coins with no access to the address can't be transacted to a new address and will become shalecoins after 10 years / or after 1 year if it's a coinbase address. Owners of possible computers with the ability to "hash" the privatekey would use these computers only for shalecoins. (Coins with no holder)