hi ratflat & welcome; PoS was turned off with the last release
If there's no POW nore POS what keeps the network secure? What is the incentive to keep a node running

I believe that staking is still providing a reward, only to the extent that transfers provide fees (which are burnt). Maybe there is no need for greater incentives anymore, whilst growth and development are ongoing.
The movement of speculative money may ensure that the network remains active enough.
This is one of the only POS coins to have reached its max-coins limit. Open wallets keep the network running .
Nobody knows what will happen, could still fail, but an interesting experiment.
NXT & ARDOR also reached max-coins (instantly on launch), that network uses forging of fees to generate blocks which keep the network secure.