Yes. This is why I made this thread before it happened and warned everyone on Discord.
Mojang enforcing Java Minecraft accounts be Microsoft Accounts with Moderation
I preemptively, predicted these issues.
You will be able to gain access to your account by contacting Mojang, but you need to be persistent & proactive. You will need your initial payment method, you may be able to search your bank account records for “mojang” or the cost of the Minecraft account at the time.
data is scattered across multiple files/database tables, there is no easy way to “transfer”, its all manual and all takes a long time. Which is why I posted out warnings to everyone to act sooner rather than later.
You will definitely be allowed to play on your new account, dont worry about that. but the best option for everyone is for you to contact Mojang with your purchase details and get the email changed.
Read the last line here https://help.minecraft.net/hc/en-us/articles/360035056531-Changing-Your-Email-Address-Mojang-Accounts-
If you are unable to change your Mojang account email, have your transaction ID or gift code available and contact Minecraft support.