We can expect that the next LTSC *after* Windows 10 Enterprise LTSC 2021 will be built on Windows 11. And it will also keep the 5 year support. However, that's expected in 3 years or so ...
The difference with a perpetual license version is that if you buy Office 2021 ... lifecycle a bit. Windows 10 client LTSC is getting five years of support now, although IoT Enterprise LTSC ...