The first new upcoming feature might be Messages' web integration. The app could become available to use on a PC through the browser, but you might have to pair up your cellphone and the computer first. To do that, you may need to visit a website on your PC, which could give you a QR code to scan with your smartphone. You'll most likely be able to use Messages as usual, but through the web interface. Google has already integrated its other messaging app, Allo, in a similar way, so we have an idea of the whole process already. Furthermore, there's a possibility you'll have the option to see all computers you've paired up with and possibly unpair with whichever at any point in time.
Last but not least, we will probably be witnessing the introduction of payments made through Google Messages. In November, Google added а similar feature, allowing you to send money through the Wallet app, but the Messages payments seem to be catered towards buying stuff rather than sending money to your friends.
The new update is currently being rolled out to users worldwide, but in case you're impatient and you want to update Messages right now, you may download it manually here (Android only)
source: Android Police