-snip- The question is is there a way to shift POW to POS without any significant impact for bitcoin.
Any move will have an impact, switching Bitcoin POW to POS is stupid.
Bitcoin can even switch to POS at any time, but is that the best way?
Please note, when Bitcoin is transferred to POS, bitcoin is no longer decentralized, POS only changes bitcoin to be centralized and that is not the purpose of bitcoin.
There's nothing wrong with using POW for bitcoin anyway,
POW is even more powerful than POS even though it uses more energy. Each Technology has its own risks,
PoW and PoS networks are equally vulnerable to
Denia of Service (DoS) attacks.
A weakness in the PoW networks specifically is the Selfish Mining attack, a condition in which attackers broadcast picky blocks to waste the computing power of honest miners.
A weakness in the PoS networkis that it is vulnerable to Bribe Attack attacks. In this condition, the attacker makes transactions and then builds a secret alternative chain before the block contains the transaction. Furthermore, after the transaction is confirmed, the attacker's alternative chain becomes longer than the valid chain where the attacker will broadcast the alternative chain. As a result, the alternative chain will be accepted as a new chain and considered valid then the attacker's transaction is reversed.If bitcoin wants to remain decentralized then PoW is the perfect network.
The use of a lot of energy can be overcome by using environmentally friendly and renewable energy, it will be a good solution instead of having to move to a PoS network which is certainly more centralized.
Any PoS coin network that has 5 people controlling over 51% of the stake is more decentralized than Bitcoin where only 4 people (mining pool operators) control over 51% of the hashrate.
The so-called bribe attack is pure nonsense. You basically created a calculations on future variables that eats up more CPU & Ram ,
in other words you created a PoW in PoS, that literally gains you nothing except more wasted energy.
You might want to actually read up on PoS.
PoS:
Staking coins compete to create the next block based on the code parameters , which different PoS coins use different code.
Staking coins go dormant, after stake decreasing % , so more than 51% is needed to attack.
Staking coins can earn rewards, transaction fees can be earned or burned depending on specific PoS code.
*Specfic to Ethereum PoS code, if you attempt a 51% attack all of your coins will self-destruct.*PoW:
Wastes enough energy to make a Grid unstable, which sets it up to be banned by Governments
Only takes the Collusion of 4 people (mining pool operators) to 51% attack for the last few years.
As PoW rewards drop, the incentive to selfish mine and collude in BTC increases.
No Limits on how long a 51% attack can last.
Bitcoin lack of leadership , means their is no one to coordinate a successful conversion to PoS.
Which would take years, as their are multiple decisions to be made and no one to make them.