What are the possible punishments to any players who don't pay the development fee?
We need to wait until the government of the Russian Federation & the State Duma will adopt the law. Now, I can say just this. Former KHL President, now the vice-president of the Russian government - Dmitry Chernyshenko - is responsible for the adoption of the law. While being the KHL President, he said a few words about the idea. It should work like with government´s funds (stipendium) to university students - you will get a stipendium from the government, but you are obligated to work a few years in Russia after your graduation is over or to give back the stipendium. It works like this in other European countries as well. You can ask yourself, how it works with these funds, if a person does not want to work in a country or does not want to give the fund back.
The Russian government funds the hockey program across the country. So, young prospects are getting an elite education, so they should give something back to the system. Either playing in Russia or paying a compensation. As simple as that.
If speaking about the international transfer rules. A player needs an international transfer card if wanting to go abroad. If the Russian hockey federation does not give him this card, due to his unpaid obligations, he can not go anywhere.
If you are liberal, you can consider this as unfair to a player (individual). On the other hand, the international transfer rules are not protecting the small, poor leagues & clubs over rich leagues. I do not understand, why CHL/USHL clubs do not pay around 100 000 USD or whatever for every European they get. Or the NHL clubs negotiating the transfer fee with the European clubs on case to case. Dahlin/Michkov worth (fee) could be 10 million USD while some 4th line grinder would be for free. That is a fair model. If it worked like that, the Russians would not need to adopt the law they are discussing now.