So on July 13, 2018 Coinbase announced that it 'will be exploring the addition of several new assets'. The list included Cardano, Basic Attention, OX, Stellar Lumens and Zcash.
Coinbase started in late 2012 so they had a huge head start on a lot of exchanges and has had quite a bit of experience with Bitcoin. They eventually added Ethereum, Litecoin and Bitcoin Cash last year.
In a post yesterday, August 3rd, they announced that they are 'exploring a range of new assets for storage only'.
Will they be charging a holding fee for the storage? Do they think that people will purchase the 'alt' cryptos and move them into Coinbase for storage?
If you have a Ledger Nano S or a Trezor, why would you move them onto the Coinbase site?
I personally think that Coinbase could have a larger customer base if they expanded and supported the top 'alt' coins. This could have been done over a year ago when the sector was 'hot'. They could have had a wider customer base as crypto enthusiasts would not need to search out specific exchanges that traded the top 'alt' coins.
But since they are just now starting to think about adding various coins/tokens, they may have seen lost $$$ as the other exchanges have swept up quite a bit in commissions trading 'alt' coins.