Right.  Otherwise we couldn't have a finite limit of 21 million coins, because there would always need to be some minimum reward for generating.  In a few decades when the reward gets too small, the transaction fee will become the main compensation for nodes.  I'm sure that in 20 years there will either be very large transaction volume or no volume.

...
While I don't think Bitcoin is practical for smaller micropayments right now, it will eventually be as storage and bandwidth costs continue to fall.  If Bitcoin catches on on a big scale, it may already be the case by that time.  Another way they can become more practical is if I implement client-only mode and the number of network nodes consolidates into a smaller number of professional server farms.  Whatever size micropayments you need will eventually be practical.  I think in 5 or 10 years, the bandwidth and storage will seem trivial.
...

Long before the network gets anywhere near as large as that, it would be safe
for users to use Simplified Payment Verification (section to check for
double spending, which only requires having the chain of block headers, or
about 12KB per day.  Only people trying to create new coins would need to run
network nodes.  At first, most users would run network nodes, but as the
network grows beyond a certain point, it would be left more and more to
specialists with server farms of specialized hardware.

It can be phased in, like:

if (blocknumber > 115000)
    maxblocksize = largerlimit

It can start being in versions way ahead, so by the time it reaches that block number and goes into effect, the older versions that don't have it are already obsolete.

When we're near the cutoff block number, I can put an alert to old versions to make sure they know they have to upgrade.