I’m kinda late to the party here, but my thoughts from the ARDC post.
The ARB token has the ability to mint 2% of supply annually, why not use this as a baseline, thus if you do not delegate, you are diluted, thus tokenholders are incentivized to remain engaged with whom they are delegating to. (Split something like 95/5 owner/delegate)
There are a ton of delegation experiments that existed in the past that should be evaluated such as Holographic Consensus (Push) or Delegation Markets (Pull). This could be an alternative to using dilution as an incentive, although there are obviously other considerations.
Tally tARB is a bit scary from a concentration of power perspective; I think if we do create an incentivized re-delegation program, it should probably be enshrined, vendor agnostic, and upgraded via governance vote. Something that would need to be agreed upon before development begins. Then regardless of how we incentivize via sequencer fees, dilution, etc we have one location that arb holders are expected to stake and receive their pro-rata share, as well as for DeFi integrations.