This line of thinking, ladies and gentlemen, is exactly what the series doesn't need and is just another "let's take the easy way out, reboot!" excuse that Hollywood has a boner for and now, slowly, the gaming industry.
You mean as opposed to the "let's make 101 sequels and milk the daylights out of every franchise that makes respectable bank" approach? That sounds pretty "Hollywood" to me as well...maybe even moreso.
Why should the timeline be done after 1999? As already said they can fit dozens more games without stepping on another one's toes. Or do you also think only 1 game is needed to fill that 300 year gap in the timeline? How about a game chronicling Soleiyu's adventures as an adult? Or a sequel to Lament that has Leon encountering the next vampire lord? Believe it or not, a lot of fans (not just here) still have love for these characters/stories and if I still see potential in the chronology, a hell of a lot more do as well.
The problem is not with the idea you propose, but rather with Konami's current handling of that timeline. I'd be all for a telling of tales that we as Castlevania fans WANT to see (Sonia, Soleiyu, Christopher, Trevor, the Belnades, etc), but Konami insists on dragging in more fringe characters with fringe storylines that often just barely thread themselves into the intrigue of the CV history. Saying "we want more of the original timeline" to Konami is just going to be-gat us another Dawn sequel, or some tale about a guy from a long line of Jacksons and some sorted nonsense about how the VK was reborn through the roots of a sacred flower and handed down to his ancestors by the mightly Pain Elemental to keep the peace until a long lost band of Belmont ninjas could make nice enough with God to be granted the right to use it again.

In short, Konami isn't answering the really interesting questions of the original continuity, they just keep posing more (most of them we don't care enough to inquire too deeply about). They're flooding this timeline with new characters when, as you said, there are already a bunch of interesting, well established ones they could further develop. If they just can't get this whole concept, then they
should just start over. Hell, they don't need to trash everything that's been built...they could just start at the beginning and redo it all bigger and better, leaving out all the convoluted stuff. Most of us on these boards really are doing nothing but pining for those older games from back in the day that made us fall in love with this series in the first place...I doubt that revisiting these favorites in a whole new light would be against our sensibilities
.
Bottom line is, both timelines can coexist, and I think Konami has intentions on doing that (why else would they experiment with 2D "HD" visuals using classic characters, or release Adventure ReBirth, if they are trashing everything about the old timeline & focusing solely on LoS?)
I don't think I ever said that the 2D titles needed to go away so that the LoS continuity could reign supreme. In fact, just the opposite. I'm a firm supporter in the idea of this franchise maintaining two separate courses as time moves forward.......a 2D one and a 3D one. I want the 2D series to continue, but I want them to stop making games that sidestep the core legend in order to tell inane sidestories about characters that have no previous basis in the canon. And as I said in the other thread: I don't believe that a stringent new timeline for the 3D titles should even be pursued. Those games should serve as a way to retell or reimagine the events of various classic CV games instead (and not necessarily in the form of flat-out remakes).