BBC Radio 4 - Today, 20/07/2015, 'It’s definitely not laziness!':
On "the distinctive Scottish rolling "R" being lost as younger Scots no longer pronounce the letter as forcefully":
Host: Is there anything we could or should do about it?
Eleanor Lawson, sociolinguist at Queen Margaret University: I don't think there's anything we should do about it.
Language changes all the time.
In Anglo-English, R began to disappear from about 1700 and originally it was a working class London feature and it was heavily stigmatized.
And today most Anglo-English speakers don't produce R at the end of words and it's completely acceptable.