RE: QB64 basically emulates an 8086 running DOS... (Really?)

RE: "So far it just emulates VGA memory"
It emulates a whole lot more than just &HA000, QB64 is built from the ground up to be compatible with 16-bit addressing, 'intelligently' accocating data/strings/arrays/etc. referenced by VARSEG/VARPTR/etc within an emulated conventional memory buffer. However, only things that have to be emulated are, so unless you actually use CALL ABSOLUTE, PEEK/POKE, INP/OUT, CALL INTERRUPT, etc you are directly accessing data. Only QB64 offers this level of QBASIC compatibility.

RE: "...but Clippy says it is useless unless it also emulates all the MS-DOS interrupts."
Adding support for the ones used by QBASIC programmers is planned.

RE: "Already it generates 1 MB executables for Hello World"
Sure, it's bloated now but that's only because it is also including support for playing mp3 files, loading jpegs, etc. Once QB64 development has progressed further, expect QB64 to generate programs which only contain the required components.

RE: "There's no way that programs written in QB64 could be as fast as hand-coded versions in C"
QB64 will support inline C integration, if programmers want to incorporate C into their programs then that choice will be made available to them. As will incorporating external libraries and DLL files.

RE "It doesn't have the nice features of other high level languages like higher-order functions"
Forgetting the fact that QBASIC doesn't have this either (so why are you here?), it's not wise to speculate about what will/won't be included in QB64 in the future. For now, QBASIC compatibility is the primary objective and giving the programmer access to integrated commands which take advantage of modern graphics, sound, interface & networking. Later down the track expect to see pointers (including function pointers) and object-orientated code supported, but not in the way you might expect from C++, QB64 will always be a language which can be understood by BASIC programmers.