The information about all of the above has been published in countless posts, in documentation, in the forums.
The changes coning was first posted in Dec 2015, then again in January 2016, then again (a few times specifically about ProPack) in July 2016 and then again January 2017 (where the clear out your bookmarks was noted).
We are constantly updating, improving and moving forward. We are adding services, we are adding features (Premier subscription gets you all that and more features and functionality) the developer has also a new SaaS project and offering. He changed the site domain to differentiate between the WordPress StorelocatorPlus and the MY SLP SAAS store locator.
You should have downloaded the latest version of ProPack and Tagalong from your account back in July. See versions here.
If you want to ensure all the add-ons will continue to work with newer versions of SLP, you should purchase Power, Experience or better value for those….Premier subscription
The add-ons will always work with the version of Store Locator Plus that was available at the time you purchased the add-ons. The individual add-ons called Legacy will eventually stop working. This has been announced throughput the past year. There is too much overhead and inefficiencies of the softwareto continue to maintain 20 add-ons. It is not cost effective and not efficient. Some of those add-ons date back 5 years and do not work as well in the current environment. Just as WordPress is contsantly updating we must as well.
If you do not want to make your site using SLP the best it can be, and you still want the outdated add-ons, then you should not update SLP beyond 4.7.2
The best way to keep informed about the technology and improvements and new releases is to subscribe to the RSS feed, follow us on Twitter or follow us on FaceBook or Google+
If functionality and appearance of your site is important to you, or if you developed a site for someone else, you should keep versions updated.