Other coins exist that share code bases with Monero. Will we cater to questions about similar coins as well or is this strictly a Monero only stackexchange?
I agree with fluffyponyza that Monero will look drastically different than every other CryptoNote coin after RingCT.
Monero has by far the largest user and development base of any cryptocurrency of CrytoNote origin. Monero.stackexchange.com will therefore remain the best place to find CryptoNote expertise (for any CryptoNote coin) even after RingCT is released.
Other CryptoNote forks (including forks of Monero such as Aeon) should always be considered on topic. Sending CryptoNote questions (that are not Monero specific) to Bitcoin.stackexchange.com seems counterproductive both in generating expert answers and in growing Monero.stackexchange.com
I would try it.
Start by being more inclusive and try not to anticipate problems before they occur in actual practice. It's not like we're going to create an endless list of emerging cryptocurrency sites, so grouping these subjects by their core code probably makes sense.
Stack Exchange scales really well. There is certainly no advantage to intentionally becoming a smaller site. Many of these products have communities of their own, so you should welcome them with open arms and hope they will contribute their numbers to this site.
This question was asked during the definition stage: https://area51.meta.stackexchange.com/questions/23731/are-questions-about-other-cryptonote-coins-on-topic
I agree with the comment below from fluffyponyza:
In much the same way as Monero questions have been considered on-topic in Bitcoin, I don't think we should be exclusionary in our attitude. AT THE SAME TIME...Monero is looking less and less like CryptoNote every day. Once the RingCT integration is completed there will be such vast differences in our cryptography that it won't even vaguely be compatible. The community will answer CryptoNote questions because that is our origin story, even though it will eventually no longer be relevant. – fluffyponyza Jun 4 at 8:32
Crossposting my answer from Area51:
I would strongly recommend to include the underlying technology (e.g., CryptoNote) in the sites scope / topic and therefore enable for smaller projects like the ones you stated to participate in this site. This will include a larger community and questions on one coin might be valid on others as well.