Since eventually Aperture will stop working for me, I'm sure, I decided to buy Corel's After Shot Pro 3 (based on Bibble Pro and now updated). I've had it a week, haven't used it all that much, but enough that I think that it is an good replacement for Aperture. The functioning is of course different, but I am finding that I can do all the things that I could do in the most recent Aperture version. After Shot Pro also can use a large array of plug-ins available either for free or for purchase through Corel. It's fast, easy to learn, does what I need and not expensive. Easy as pie to download and get up and running, the way it should be.
It probably does not have all the bells and whistles of LR, but it does what I want/need. Keep in mind, I don't make my living taking pictures.
You can download the pdf user guide to get an idea what it can do, good way to judge if it's right for you. The descriptions of the plug-ins on the Corel site are also done well.
I just thought that given the reluctance to adopt Adobe products that has been expressed on these pages by some others, and the seeming inexplicable exit by Apple out of "advanced" applications, people might be interested in this tool. I believe it is underrated.