Good news: I successfully changed profile Id in this saved profile!
I would like to understand how to change an existing profile to unlock all premium cards, but I still don't find a working method (profile file is encrypted); however even to use this profile with another Steam Id may be usefull. Indeed, I think that adapting this profile to work with another Stem Id may let you use it for online multiplayer (I didn't test: actually I don't like to play using genuine Steam). Furthermore, for multiplayer games, even with SmartSteamEmu you need to use a different Id from your opponent (you cannot use both 2183355).
This is a brief guide for changing Id in this saved profile.
Open YOUR current saved profile file in a
Hex editor and annotate first two and last two bytes (in exemple, but yours will be different: BF BD and D3 BE). Then, open THIS saved profile file (with all the cards unlocked) in a
Hex editor; you'll see that second byte is 9F. Do a XOR (bitwise operation) between first two bytes you annotated (ie: BF Xor BD = 02) and then between result and 9F (ie: 02 Xor 9F = 9D). Write what you obtained (ie: 9D) as first byte overwriting previous one (it was CF). Now do a Xor between the new first byte and first byte you annotated (ie: 9D Xor BF = 22) and then with last annotated byte (ie: 22 Xor BE = 9C). Finally, overwrite last byte (it was A0) with result (ie: 9C) and last but one (it was D4) with last but one byte you annotated (ie: D3), and save over your previous .profile file (after you did a backup copy, maybe!).
Now you have to create a new hash.file file using hash generator (you can use hash generator for Magic 2014) and to overwrite old one.
If you did everything correctly, when you start Magic 2015 you'll have "everything unlocked" profle and you can personalize it creating your deck!
PS:
Sorry if my english is not good and if I wasn't clear...