what can I use in the future that are just as good as this programme??
I have not found yet a perfect replacement.
I keep my main library in Aperture. It is working reasonably well on El Capitan.
A selection of my photos, mostly the 5 star photos, I have migrated to Photos to sync it to all devices using iCloud Photo Library.
But the editing and organizing tools are limited compared to Aperture; it is a decent successor to iPhoto, but not for Aperture. The editing tools are getting better, now that their are more Photo Editing Extensions available, the problem is, that there is not much customization for the workspace, the database design, the metadata presets.
If you like Adobe PhotoShop, Lightroom would be the obvious successor to Aperture.
The look and feel of Capture One is closer to Aperture than Lightroom's, however. Both have advanced editing tools and very good RAW processing.
I have explored neither of them close enough to be able to recommend either one.
When Aperture stops working, I'll probably go back to open source software. The rest of my family is using digicam and GIMP on Linux.