One interesting concept @starkerz put forth is the option to lock up your powered up STEEM for a longer (or shorter) period than 13 weeks in exchange for a higher/lower curation reward. This would act sort of like a STEEM bonds system. Also, another idea regarding this, could be the possibility to trade STEEM bonds on an open exchange and let the market decide what the interests rates should be for the bonds.
Even as a minnow, I would definitely have no problem locking most of my STEEM for 1-2 years if this behavior would be incentivized with higher curation rewards.
Would absolutely support this proposal for a future HF.