It may be technically possible to write some drivers with Delphi, but as far as a general answer goes, I’d say: you can’t easily write drivers with Delphi.
First, there’s a difference between user-mode driver (UMDF) drivers and kernel-mode (KMDF) drivers. UMDF drivers should be possible with Delphi. KMDF drivers aren’t easily possible though, because
1) Delphi’s linker can’t produce them and
2) Delphi’s object file format is different from the COFF format the Microsoft linker uses by default.
3) Delphi’s RTL makes the assumption it lives in user-mode and may do certain things that one shouldn’t do in kernel-land (I think e.g. of the way exceptions are handled; also different memory management), so you’d have to be very careful on which RTL functions are safe to use. There are also difficulties with System and SysInit units (see the comment by Ritsaert Hornstra to another answer here).
I’m not saying these aren’t problems that cannot be overcome (cf. the post you link to) if you’re really dedicated, but it won’t be straightforward.
Secondly, KMDF drivers (I don’t know about UMDF, actually – can anyone comment?) for Win64 have to be in 64-bit code. Since currently, there is no 64-bit Delphi compiler, writing them is a definite no-no.
The Wiert Corner - irregular stream of stuff 
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