True sir ,but, Plant sings with a lot less stress and power on his solo tours of late. The 1980's stuff was different. He actually screamed and growled through a lot of those tours but he has since made a point of singing and writting much more melodic/falsetto type things a lot more than not; ie; The new albulm with Allison. He cannot do that nearly as much with Zep and the band knows that.
I believe they will opt for a small number of shows in the biggest of venues except for a scant few select small venues because of the history they represent like say, Royal Albert or some place like th