interesting topic. Is it possible to pay dividends in other coins, and control only the shares with namecoin?
nope
Actually I think the differences between namecoin addresses, bitcoin addresses and so on are merely cosmetic really, you take the same key and put a different prefix on it resulting in a different checksum and that gives you a different type of coin's so called "address" based on the key.
Thus you could actually take the same key you used for a namecoin address and create from it a bitcoin address, or litecoin address, or i0coin address, or ixcoin address, or whatever, using the exact same key.
Thus it should technically be possible to pay someone any type of coin simply by taking their namecoin address and building instead the equivalent address for some other blockchain.
It is even helpful that namecoin does not (at least not yet) have so called wallets out there yet that send coins on people's behalf without the person actually controlling the address the coins are sent from, as this means it is currently pretty certain tht an address someone sent namecoins from is an address they have the private key of, thus an address they could accept any kind of coins at on any blockchain simply by importing that\ key into the appropriate blockchain's wallet.
-MarkM-