Ouch, at this late date why start over as a Proof of Work blockchain?
All that will do is perpetuate your vulnerability to fly by night miners.
Then if you also plan to not honour the existing coins, well, that is total ass-hat-ery.
Money is IOUs, to deliberately renege on the long long history of IOUs (coins) already issued (minted) is awful.
Have you considered, rather, the approach taken by the
Galactic Milieu to rescuing "dead" or "endangered" Proof of Work coins, which is to issue tokens on a tokens platform (for example
HORIZON or
Stellar) and implement 1-for-1 bailing-in and bailing out of the actual on the blockchain coins for the corresponding tokens?
(Heck, forget about bailing out even maybe, just have bailing-in to permit any already existing coins (IOUs) on the blockchain whose private keys turn up some future year or century or whenever to be redeemed for the token; do you really need continued minting or is that simply potentially devaluation-causing inflation?)
That approach can not only allow the value of the coins to continue to be transacted even while the blockchain itself is running slow due to the attacks of fly by night miners but also can secure the value of the coins against mining attacks of such power that they re-org the blockchain, re-writing history, since the bailing-in process can if need be wait for any coins wanting to be bailed in to first be secured by hard-coded checkpoints in the coin daemon before issuing the tokens representing such newly bailed-in coins.
At very least do not be so dis-honourable as to deliberately fail to honour the project's existing coins (aka IOUs) it already issued / minted!
Being honourable would make it more feasible / reasonable for any similar mechanisms to the Milieu's to continue to represent your coin with its tokens; rug-pulling such as you seem to be potentially proposing is not a highly condoned behavior in the finance space nor the crypto space.
-MarkM-