Your traffic at end of 2020 will determine values as it isn't going to be in the name. RegFee.
If you already owned artpal and wanted to add a shop then fine but your just promoting artpal at 5% so project your sales you make till 2020 to offer your referral model for sale.
You will likely make more promoting the art itself than the sale of the domain name.
I voted bad as you have no option other than to promote it or drop. If any TM's I didn't even look could spoil your plans.