You can download a free trial copy here. Last's about 30—40 days.
http://www.pixelmator.com/pro/free-trial/
Unfortunately there is no discount if you've previously purchased Pixelmator. Full price.
I think the developers will be putting all (most) of their energy into PXM Pro. Maybe a few more updates for the Classic version. But I wouldn't expect any more features. Only bug fixes.
Below in an earlier post I mentioned some features that have been removed from the Pro version.
https://www.reddit.com/r/pixelmator/comments/7guc3p/pxm_pro_missing_features_complaints/