In the comments of today's Sony blog post, a company employee confirmed that the new adapter only supports a single DS4 controller, but you can "connect a second controller with a USB cord" to play multiplayer through PS Now. That makes the Dualshock 3 the best choice for emulating PS2 games with PCSX2. It appears that this will work with up to 4 controllers. When you are done it should work perfectly via bluetooth What I just discovered today is that this works with multiple controllers.
The PS3 controller, Dualshock 3, has something the best PC controllers don't have: pressure-sensitive analog face buttons. Basically you just connect the Dualshock 3 controller to your PC via USB, install the Xbox 360 controller drivers, then follow the guide. But it's nice to see the company itself being more active across platforms, so you won't need to turn to third-party tools anymore. Nowadays, although the PS4 has stolen the spotlight from the PS3, you can still get plenty of use out of your PlayStation 3 controllers. Sony probably assumes most people will be getting the adapter for a more convenient experience when playing PS Now (in the case of PC) or streaming PS4 games over Remote Play (both Windows and Mac). You can already use the DualShock 4 for the basics by pairing over Bluetooth or plugging it in directly with a USB cable, but now the controller's full capabilities will be unlocked. Specifically, Sony says the dongle opens up full access to "buttons, analog sticks, touch pad, light bar, motion sensors, vibration, and stereo headset jack" - so long as those features are all supported by whatever game application you're using. Today, alongside the announcement of PlayStation Now's upcoming release on Windows, the company revealed a new $24.99 USB adapter that will enable "every feature" of the PlayStation 4 gamepad. Sony is bringing official DualShock 4 support to Windows PCs and OS X.