That's why
eltoo was proposed. It will be an alternative to the current penalty system.
A softfork is needed. Also, it's not possible to spend all funds that are locked up in the channel - there is such a thing as reserve which is a minimum balance that channel must maintain. For example, one of my channels has 0.0049 BTC capacity; the reserve is 0.000049 BTC.
Thank you for your time reading the article ! Yes it cover many cases with offering a solutions to remedy the problems.
Eltoo solve the problem by continuously updating payment channel balances off-chain.
Soft fork is required since SIGHASH_NOINPUT flag for signature must be introduced to Bitcoin Protocol to make it working.
I suggest you to edit your post and add this basic video explaination about how LN works:
https://www.youtube.com/watch?v=rrr_zPmEiME