Google does give the option for users to link additional accounts. The following information can be found in Google Support Documents:
Sign in to multiple accounts at once
Tired of always signing out to switch between your accounts on your own computer? Whenever you need to switch accounts, just click the Add account button to sign in to your other account(s) and conveniently switch between them.
![Multiple sign-in does not merge account data, and it does not give one account access to another.](https://i.stack.imgur.com/MCVtr.png)
Multiple sign-in is most convenient to use on devices that you don’t share with other people (where you won’t need to sign out to let others access their own accounts).
Sign in to additional accounts
- Sign in to a supported Google product.
- Click your name or email address at the top of the page.
- Select Add account from the drop-down menu.
![Account information while signed in to one account](https://i.stack.imgur.com/9PABi.jpg)
- On the page that opens, enter the email address and password for another account you wish to access, and click Sign in.
![Screen Shot of Sign In](https://i.stack.imgur.com/8KRMt.png)
Switch between accounts
Once you’re signed in to more than one account in the same browser, you can easily switch accounts. Just click your name or email address at the top and click on the email address you’d like to sign in to.
![Account information while signed in to two accounts](https://i.stack.imgur.com/GrViK.jpg)
Products that do not support multiple sign-in
Some Google products and mobile versions of Google products do not support the use of multiple accounts in the same web browser. Instead, they default to the first account that you signed in to from your current browser.
If you want to use an account with a product that doesn't support multiple accounts, you have two options:
- Sign out of all your Google Accounts and then sign in to the account
you want to access.
- Sign in to another account using a second web browser Learn more.
Signing out
If you choose to sign out of any account while using multiple sign-in, you will be signed out of all your accounts. To resume using multiple sign-in, you will need sign in to one account and then use the Add Account option to sign in to your other account(s).
Two months after, no satisfying solution appeared, so I gave up and:
- Created a new Gmail address
- Used the Gmail address to create a new Google Plus page for the product
- Used the Gmail address to create a new YouTube account
- Created a new YouTube channel linked to the Google Plus page
Drawbacks:
- All of the past YouTube videos stay on the old account, lowering discoverability in both ways
- Likes/followers are split into 2 accounts
- Have to follow statistics for both the old and new accounts
UPDATE 2015/07/28: Google has just announced that it will finally uncouple YouTube from Google+ so the procedure will probably become much easier.
Best Answer
In the title it is stated that this is optional for channels.
As outlined in the first paragraph this is not required. Just something Channels may want to do. Weather you'll be able to keep your accounts separated is in the hands of Google