The answer is maybe.
Fans are expendable components and whey will fail over time. The only question is when.
I'll just quote Wikipeida here
Sleeve bearing fans use two surfaces
lubricated with oil or grease as a
friction contact. Sleeve bearings are
less durable as the contact surfaces
can become rough and/or the lubricant
dry up, eventually leading to failure.
Sleeve bearings may be more likely to
fail at higher temperatures, and may
perform poorly when mounted in any
orientation other than vertical. The
lifespan of a sleeve bearing fan may
be around 40,000 hours at 50 °C. Fans
that use sleeve bearings are generally
cheaper than fans that use ball
bearings, and are quieter at lower
speeds early in their life, but can
grow considerably noisier as they age.
Rifle bearing fans are similar to
sleeve bearing, but are quieter and
have almost as much lifespan as ball
bearings. The bearing has a spiral
groove in it that pumps fluid from a
reservoir. This allows them to be
safely mounted horizontally (unlike
sleeve bearings), since the fluid
being pumped lubricates the top of the
shaft. The pumping also ensures
sufficient lubricant on the shaft,
reducing noise, and increasing
Ball bearing fans use ball bearings.
Though generally more expensive, ball
bearing fans do not suffer the same
orientation limitations as sleeve
bearing fans, are more durable
especially at higher temperatures, and
quieter than sleeve bearing fans at
higher rotation speeds. The lifespan
of a ball bearing fan may be around
63,000 hours at 50 °C.
Fluid bearing fans have the
advantages of near-silent operation
and high life expectancy (comparable
to ball bearing fans). However, these
fans tend to be the most expensive.
The enter bearing fan is a variation
of the fluid bearing fan, developed by
Magnetic bearing or maglev fans, in
which the fan is repelled from the
bearing by magnetism.
So having fan on all the time will decrease its lifetime. How big impact there will be on fan's lifetime depends on conditions in which it operates. Fans usually die because dust gets into their bearings and damages them. After that fan will slow down and start emitting grinding noises. This will reduce airflow causing even more dust to accumulate and increase of the temperature. As temperature increases, dust will start to bake. At one point it will into into black solid substance and grinding noise will become even louder and fan speed will decrease even more causing temperature to increase. Sometime after this step, serious overheating problems will appear and computer will start to shutdown. At one point fan will fail and will have to be replaced.
If the fan and heatsinks are regularly cleaned, the impact from dust will be much smaller and fan will have longer lifetime.
So in the end if you can regularly clean the fan, then in my opinion there is no great cause of concern. If you can't regularly clean the fan, then having it running continuously will decrease its lifetime. Unfortunately, I'm unable to estimate by how much will the lifetime be decreased, so I don't know if it will make an impact on the lifetime of the whole computer.
Also keep in mind that laptop fans are usually more expensive than standard desktop fans.