It's a non-problem.  The market will fix it.  Miners will mine the txns with the best fees.  Don't worry about prices.  The market sets them. They are never what payers want them to be anyhow.

Has anyone considered the practicalities of doing side-chains in MRO?  Moving mining to side-chains can help deter centralization of control in the hands of a single pool operator.  I'd been given short shrift for this notion as applied to BTC, but I think my critics are simply not thinking it through:  The idea is to mine on a dedicated side-chain, and merge-mine the main chain.  If you want to insure that there are a minimum of 100 pools, you can mine on 100 side-chains simultaneously, round-robin to insure fractioning the hashpower.  I haven't considered how this would be implemented in MRO, however.

Regarding chain bloat, garbage-collecting the chain would be a big splash, and get some attention.  Define a minimum balance, and let miners reap dust.  That number can change over time.  The block chain only needs to contain an effective record of the current assignment of non-zero (greater than dust threshold) balances.  Historical data is not required to maintain accounts.  It is currently used to compute hashes, but does not need to be:  The most up-to-date assignment ledger state can be used and old stuff discarded.  This will improve privacy to a small degree as well, although obviously its not in any sense a protection against evesdropping history maintainers.  If the chain is garbage collected, then there is precious little reason not to require a minimum mix.  The requirement to garbage collect the chain insures that mining is done by CPUs -- and it's not make-work, but actual useful work.