One package for the Classic and Lightning apps without My Domain

Question

We have an app built for both Classic and Lightning UIs and we need to roll out it to the customers as one package.

We do not want to force customer to set up the My Domain in each Orgs where they install the app as managed package includes lightning custom component.

1. Is it possible to have one package to support both Classic and Lightning modes without requiring My Domain?
2. What are people doing on the AppExchange where they have only one package, but they would like to support end-users who may or may not have My Domain active?

EDIT: 3. If we enable My Domain in our packaging org, will it impact our existing package or create any dependency?

Question referenced from https://developer.salesforce.com/forums/?id=9060G000000IAPPQA4 but I have similar use case.

Answer 1

As the documentation says:

You must deploy My Domain in your org if you want to use Lightning components in Lightning tabs, Lightning pages, as standalone apps, as actions and action overrides, as custom Lightning page templates, or elsewhere in your org.

When My Domain isn’t deployed in your org, user interface controls related to Lightning components may be hidden or inactive. Lightning components added to pages, tabs, and so on, don’t run and may be omitted, or display a placeholder error message.

For orgs without My Domain, they won't be able to use your Lightning components, etc. However, nothing in the documentation states that the package can't be installed. As such, you should be able to have both Classic and Lightning elements in the same package without any major problems.

In fact, there was a question about how to "require" My Domain to install a package, so you can see what the error looks like. It's possible they've fixed the error since then, but all you really need to know is that if they don't have My Domain, they'll simply get an error if they try to use your Lightning Components.