RAH left behind some very good minds to follow in his footsteps. Perhaps the most closely tied to his legacy are Jerry Pournelle and Larry Niven, who were his proteges, in a way. He guided a good bit of their early career and, together, they formed a big part of LASFS in it's heyday. RAH even plays a part in a couple of their collaborations, along with themselves, as characters (SF writers, of course).
Niven and Pournelle are both capable of exploring some fantastic hard science in an extremely capable manner and of creating some really fund stories. Even some of their older stuff, where the science has been superseded by things we have learned since, are still great reads.
Unfortunately at least one of them, Larry Niven, has also fallen afoul of RAH's descent into sex obsession in later books. The next to last Ringworld book, Ringworld Throne, had way too much Rishathra in it for me. Same as Heinlein's last couple of books (though I did love Deja Thoris in Number of The Beast. Niven and Pournelle are at their best when they write together, such as Lucifer's Hammer or Footfall.
There are a stable of good SF writers working out of Baen Books as well. My favorites right now are John Ringo (great military SF books) and Eric Flint.
There are still dreamers who dream and warriors who will fight the good fight. Sometimes they are one and the same.
Shades of the distant past.
I was reading this old Heinlin thread and noticed your phrase "a clank to it."
Yeah...that's what's been missing. SF needs to get its clank back.