I don't know about long term support. But for the 2025 program that comes out in November 2025 you will need Windows 11, don't know what you need for Mac. Yes there is an Online version you can use on either Windows or Mac or a mobile device like an iPad or iPhone.
If you want to switch to the Online version next year here is some info……
If you used the Desktop program for 2024 here’s How to transfer into the Online version, expand the blue link if you used the CD/download last year
https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/transfer-last-y...
And see How to switch and transfer from the Desktop program into the Online version........
https://ttlc.intuit.com/community/tax-topics/help/how-do-i-switch-from-turbotax-cd-download-to-turbo...
If you used the Desktop program before you may notice several differences and not like the online version. It has less features and no Forms Mode. And you will have to pay first to see all the forms. All the Online versions do not have the same forms so you may need to upgrade to a higher version. You can only do 1 return per account. And pay for each account. You can use the same email for 5 accounts. Federal and state are separate fees.
Your return is only saved online so be sure to save both the .tax2025 data file and the pdf file to your computer when you are done. In case you need to amend in the future or if you need a copy to get a loan or something. You might not be able to access your online return when you need a copy.
