If you truly want to make a long-term coin, I would suggest a few things:

Changing the POW algorithm.

Changing the POW algo gives the coin the ability to grab its own long term miner share. Make it minable only by CPUs. Take a look at Hokkaido or MBound.
Also, consider a Bell curve for generation so that after 5-6 years your generation rate starts dropping until there is a fixed inflation of 2-3% per year forever. This will actually make the coin useful in a future economy, and is on par with the inflation of the world population and even the mining of precious metals such as gold.
I would also suggest having at most 2 decimals, if Bitcoin started at Satoshi levels instead of Bitcoin when pegged on exchanges, it would've been much more psychologically attractive to buyers. $1 for 980k ish Satoshi sounds better than $100 for 1 Bitcoin for the "terminally stupid.".

Since value will obviously be small to begin with, you could take the example of Ripple, where things are traded for 100K Ripples for example, rather than the much more confusing .001 BTC or 1mBTC, with the added pressure of this having to change again to uBTC and Satoshi at a further point in time when the value becomes too great.

Say you tried to mimic Bitcoin which has 2,100,000,000,000,000 total units, your block reward could start at 1 billion (equivalent of 1 in 21,000,000 units) and increase from there. Denominating trades in 1 billion currency units is not unheard of, obviously, and will lead to a lot less problems down the road.
Not naming it -coin. 'Ripple' sounds much better than 'bitcoin' and is definitely more SciFi/futureish than -coin. It will also help differentiate the new currency among the plethora of alts.