The iPhoto library can be imported to any new Mac, be it iPhotos app, or Photos app.
When you start iPhotos or Photos holding the Option key, it will prompt you for the library you want to open. Choose the iPhotos library and it will use it, or import\convert it to Photos. If you go this route, move the iPhotos library to the new Mac's Hard Drive unless you want to keep it on the external HDD.
[doublepost=1514387329][/doublepost]iPhotos will only be present on a new Mac if you have a way of installing it from a backup of your old Mac. For instance, when I got a new Mac, I used a Time Machine backup from an old Mac to restore apps, settings, files, etc. iPhotos is still available to use. But, if I got a new Mac and started using it without restoring old apps and files, Photos would be my only choice.