A lot of the best rock music might have been written in the 60's and 70's,and that the rest of musicians(or if you prefer"musicians")are just adding their own style to it.But as long as people inhabit this earth,or wherever/whatever else they inhabit,there will be good music being put out.Good here depending on who you're talking to.Coz music is about people and their emotions,experiences,whatever.
And besides,what is so special about 1960-1979 that no can write better music than that written then?The food they ate?Cosmic phenomena in this timeframe?
Clapton is/was great,but all the elements that inspired/drove him are still there.And they(the elements)are still potent enough to inspire/drive someone else(elses).
At the end of the day,we're all people.Period.