LONG ASS POST!!
You have to keep in mind that SCIV status of "remake" was made up to rationalise its position in canon after the fact. Before IGA there was no canon, everybody did whatever they wanted. My personal theory is that the story of the NES games, which formed a small cohesive canon by themselves, was basically finished, with no more holes to fill. CV3 told the origin story and CV2 was the definite conclusion. Therefore, they basically rebooted the storyline with SCIV. Simon and Dracula are back, only the setting is different. That's my personal view of the game.
While you *can* take the first three games like that, they most definitely left CV2 open to further sequels and there is no reason to exclude CVtA or it's sequel.
SCV4 is a remake; there is no doubt about it.
But just for clarity, let me explain what certain terms mean to me.
Port: a recreation of a game that was originally on a different platform with the exact same story, setting, and game play with minimal to no changes.
Remake: a revision of an earlier game that retains the majority of the original game play mechanics and retells the same story.
Reboot: a complete reimagining of an existing game series with minimal story elements and varying game play mechanics reused if any at all.
SCV4 was originally titled Akuma-jou Dracula when released in Japan.
It has nearly the same story in it's manual as Akuma-jou Dracula for FDS/FC and Akuma-jou Dracula for MSX.
The only difference being that Christopher Belmont and the details of his battle with Dracula are not mentioned at all.
The majority of the game play mechanics of the original game are still intact with numerous upgrades.
The setting has been greatly expanded with little left to resemble the original.
That fits my definition of a remake and it does not match a port or a reboot.
On a side note, CVX68k falls somewhere in between a port and a remake being partially a port of CV1 and of SCV4 simultaneously.
Then there is Haunted Castle which leans much more towards reboot than any of the other remakes.
Anyway, back to the issue of the original trilogy, there is another way to look at it:
CVtA -> CV1 -> CV2
Analysis:
*Akuma-jou Dracula (FDS/FC) manual states specifically that Dracula is resurrected every 100 years. Then it continues to state that the previous Belmont to defeat Dracula was Christopher.
*Akuma-jou Dracula (MSX) manual matches the story of the FDS/FC version and further specifies that Dracula was sealed in the Tower of Colbert.
*Dracula 2: Noroi no Fuuin (FDS) manual states the game takes place 7 years after CV1. Simon is only specified to have dies in Ending 2. And I should also note that the original Japanese wording says that the people will pray for a young man like Simon will appear
one day to fight evil. That is a very different tone from the localization that sounds like they are talking about a specific young man.
*Dracula Densetsu (GB) here is where the series first began to have problems. The story here states that Christopher is fighting not the Vampire Dracula, but the Sorcerer Dracula. IIRC it was stated in some interview or something that CVtA and CV3 were developed simultaneously. However, CVtA came out first.
The game itself, though fits in very nicely with the story set forth in the manual of CV1 for both FC & MSX. The only thing missing is the Tower of Colbert, which we can only assume is somewhere else and that the sealing takes place after CV2BR.
So there you have a very concise trilogy with no plot holes.
As I mentioned the first problems with first few games happens because of the contradiction between CVtA and CV3.
*Akuma-jou Densetsu (FC) manual and game intro both state that the game takes place in the 15th century. The manual states that the story takes place more than 100 years before Simon Belmont's time. Finally, it states that Dracula is already a vampire which retcons the story in the CVtA manual.
If Dracula became a vampire before the events of CV3 which is implicitly stated to take place more than 100 years before Simon's first battle with him, then he couldn't have been a non-vampire sorcerer 100 years later when he was resurrected in CVtA.
Mind you that all of this is before there was an official timeline or any concrete dates were specified in the games and their associated works.
As of CV3 we know that CV3 takes place the 1400's presumably some time after the real world death of Vlad III Dracula in 1476+.
Because it is stated in every manual to date that Dracula is resurrected every 100 years, CVtA must take place some time around 1576.
Thus, CV1 happens in 1676+ and CV2 7 years later in 1683+
My guess is that CVtA and CV3 were originally going to be two tellings of the same story but CV3 was then placed before CVtA some time during development.
Of course, with little direct evidence from beta versions of the game I can't say that for sure.
Really the only clue to this is that Trevor's real name is Ralph
C. Belmont and both games state that Dracula was a human sorcerer before becoming a vampire.
However, the most plot hole free version of an original trilogy is definitely more CV1/CV2/CVtA than CV1/CV2/CV3.