Following posting of this news item by Romera, I sent an e-mail to another silver mining company that I have shares in to get their take on it [as I didn't think I'd get an answer from Aurcana].

Here's their reply ... doesn't sound like we have much to worry about:

"The discussion of mining royalties in Mexico have been going on for more than a decade; however with the (new) federal government in place, it’s become a key part of their political agenda. 

We would not be surprised if there is a 1%-3% royalty imposed on the mining industry in Mexico over the next 12-18 months.  However, the rumor is that any support and donations in local communities would be a credit against the federal tax.  

However, it’s still too tell what the final plan will look like."