LUHE: "I read somewhere that some scientists believe that Homo sapiens and H. neanderthalensis both evolved from H. heidelbergensis. Is this view still held?"
Here is some relevant info from the Smithsonian site regarding that question--Homo erectus:
[One several] still unanswered questions about Homo erectus that may be answered with future discoveries: Was Homo erectus the direct ancestor of Homo sapiens, our own species?
And also:
Evolutionary Tree Information: Some scientists distinguish between the African (Homo ergaster) and Asian (Homo erectus sensu stricto) fossils of this taxon, while others lump them together as Homo erectus sensu lato. In either case, there is general agreement that it descended from an earlier species of Homo (e.g., Homo habilis) and represents one of the widest dispersals of early humans in our evolutionary history. It is likely that distinct populations of Homo erectus sensu lato led to the emergence of later hominin species, such as Homo heidelbergensis, and ultimately to our own species, Homo sapiens.
At the beginning of its time range, around 1.9 Mya, H. erectus coexisted in East Africa with several other early human species including Homo rudolfensis, Homo habilis, and Paranthropus boisei. Sometimes they were even found at the same fossil sites. At the end of its time range, around 143,000 years ago, it coexisted with Homo sapiens and possibly Homo floresiensis in Indonesia.