Correct. In fact, without google play services, the Photos app will no longer display any options for cloud sync or account login, which is nice actually. Keeps the appearance clean. That said, the photos app will still connect to google to upload analytics unless you block it with a firewall app like Netgaurd.
I manually transfer my photos. Something you could try if you want to keep uploading photos to your google cloud is to login via the website and try and upload them that way... I'm not sure, never tried it.
Cheers