In fact merged mining made XDN blockchain 10x times more secure than it was before. The recent XDN price drop is caused by Polo delisting and panic sales there. I believe there is no connection between the price drop and merged mining because it only made XDN stronger.
Actually the mistake was done much earlier, in order to have a secure blockchain the block_reward * price should not be too low, preferable the price should rise much faster than the decrease in block reward since a higher price would make the coin more attractive to an attacker. The btc block reward is now 1/4 of the oridginal reward but the price is 300000 times higher.
The fact that a majority voted for merged mining + PoA does not mean it is a good idea. Now you will depend on XMR miners for your security, 10x hashrate does not mean 10x security. Preferable solo GPU+CPU mining should be easy but now with merged mining you have made it pointless to mine xdn using the wallet.
The only solution i see is starting over with a new coin but then everything needs to be finished so no hardforks will be needed, maybe XMR without ringct if that is bad, maybe a better version of zcash, a PoA/PoW version of SDC maybe?. I will be honest, i do not really understand how these anonymous coins works and i guess most investors have no idea what they are buying when they invest in dash, xmr, sdc, zcash or whatever. Of course establishing a new coin is very difficult and long term holding is very dangerous
http://www.truthcoin.info/blog/altcoins-are-not-coins/ (btw: i hate btc).