The offer might be extended beyond that. Or there might be a new offer. Or there might be a real upgrade for existing users. But we don't know and can only guess, as there is little clear communication from MAGIX on this subject at the moment. There is talk of email upgrade offers being sent out by MAGIX but it is unclear who will receive them and who won't, and whether the pricing will be any cheaper than those offers above.
The email offer I got contains the links you posted above. There doesn't appear to be different price for an upgrade. It appears to be the same whether you buy as a new customer or as an existing user.