I suspect that they will stick with their tried and true software, but
this is just speculation on my part. They are always tweaking their
software apps. Rumours persist that Evolution will be replaced by
Thunderbird for example.

Change is good, but too much change at once may cause a backlash.
Canonical is smart enough to know what users will put up and what they
won't. I suspect after using GNOME Shell that they realised that it
was too radical to be adopted by their user base and that it will take
time to grow on them. I also think that they foresaw this coming and
have been thinking about this for some time. The next logical step for
Ubuntu is to have its own desktop environment and Unity is a step in
that direction.

I only throw this out for discussion. It may also keep some users from
upgrading to Maverick and then to Natty which is not necessarily a bad
thing in times of change. If you are using Lucid, then don't just look
ahead to Maverick, but look beyond to Natty. Lucid is LTS and there is
no need to go thorough this and be a guinea pig. Just sit tight and
see where things go. You have three years of support from last April.
If you have already upgraded to Maverick, remember that it will expire
1 year before Lucid, so you are on the upgrade treadmill whether you
like it or not.