I do not think it will be made illegal any time soon IMO. Salvia has been around in the UK for quite some time now. The government will clearly be aware of this, if they had thought it posed a serious threat it will have been banned much quicker. Right now, I do not believe it is on the governments urgent agenda of drugs to ban. It is quite clear that the government is happy to impose bans on new mind altering, that pose a threat to the nations, substances such as Cathinones. Which shows that it would be easy for the goverment to ban Salvia. Because no effort has been made on their part to ban it so far, I think it will be a while before it is banned.
After all, it is a reasonably safe drug and is not at all addictive.
People spend their lives searching for perfect moments and fail to see, that there are many unappreciated perfect moments everyday that are overlooked.