I received an email from trainsim.store back on 10/25 (I think this would fit under the Trains & Drivers board since it used to be called trainsanddrivers.net), and here is what it said:
"For almost half a year now, the interest for TS1 content in Trainsim.Store reached an all time low. Thus we're paying more service costs per month than we get revenues from the addons.
As it seems to keep as it is right now we sadly have to announce that we will shutdown the website by the current fiscal year on 31.12.2021
If you want to keep your paid content make sure to have a copy and download it by 31.12.2021.After that date you will not have access to your files any longer.
There will be also no additional sale. If you want to get some addons your chance is now.
Thanks for your support for the last years, your's Matthias."
Did anyone else get this email as well? I sent out an email asking if there would still be support for purchases after the closure of the site, but haven't heard back.