this has been raised before, and Saltyspoons response was for people to use the naming convention [LTC] at the start of the thread title.
The big problem with this is there is not even an ignore thread feature, nor a saved search feature. So not only can't you focus in on just the topics you want, you can't ignore the others.
Given that this forum is seems to be locked in a time capsule when it comes to feature development, it seems like using the capabilities it does have (creating subforms) as a workaround is the best possible.
As far as Bitcointalk vs. Altcointalk if I'm not mistaken most of the traffic is in the altcoin section, i.e. that's where the bread is buttered and I don't see it going anywhere. Maybe to reduce confusion among people who don't understand what is going on they should just rename bitcointalk.org to altcointalk.org and move what little Bitcoin discussion is still here down to its own subforum.