.....I think there should be an enhanced 68k standard that at least adds ColdFire support. These few useful instructions are already supported in some assemblers, compilers, etc. and only need to be enabled. We came up with a few other instructions that would also be great potential 68k enhancements. I think the fpga Arcade folks see their machine as more for retro game enthusiasts that would not want such enhancements but rather maximum compatibility. I think they are wrong. I think it's possible to have excellent compatibility and the enhancements. How do we convince them? Start a poll?
There are a few people working on 68k softcores separately and AFAIK they are all adding some extra instructions beyond 68000 and even 68020, but I don't see much point in adding Coldfire support to a system that is going to have its CPU inside the FPGA, unless there is some Amiga software already written that needs certain Coldfire instructions. Or if adding Coldfire instructions will allow new software to be written more easily than could be done with 680x0 instructions alone. As for starting a poll to convince the FPGA Arcade inventor of anything, I would say no. I have not seen anything written by MikeJ that indicates he is limiting the use of the Replay board in any way and anyone can modify what is loaded into the FPGA to do anything they want. Just don't expect MikeJ to do it for you if you want something different than what he is offering.
SAGA is written in AHDL which is only compatible with Altera FPGAs. It would have to be completely re-written in VHDL or Verilog to use with an Xilinx FPGA like in the FPGA Arcade.
I am not familiar with AHDL, VHDL, or Verilog code, but I would be surprised if there is no conversion utilities available and that it would have to be completely re-written from scratch.
AAA as it would have been implemented in the 90s would be surpassed by even integrated Intel graphics nowadays.
SAGA as implemented in the Natami should be a lot faster than what AAA would have been, even if it isn't exactly what AAA was specced as.
Yes, SAGA will be much better and faster than what AAA would have been, but still SAGA should not be compared to any other PC graphics system or card of today. It is not being developed to compete with today's standards, but to provide the best and fastest "Amiga" experience. An expansion of 1985 technology to see how far that old tech can be pushed forward, not to change it into something more similar to what is available today.
.....Whats the point in it, when current Amiga graphic cards can out perform it ?
The point is to advance the Amiga chipset past the point that Commodore ever developed it, so that people that still want to tinker with, and code for the original Amiga in the same way it worked from the beginning, can work with something that is faster and better than the original OCS, ECS & AGA systems. It is not for everybody, but a lot of current and former Amiga users are excited about seeing what "Might Have Been", if only things had been run differently at Commodore.
I figure the new implementations of the Amiga gfx advancements like AAA are just an homage to what "could have been", a spiritual successor, tbh. I'd be very surprised if there is ever much software that takes advantage of it, but as long as it maintains backwards compatibility, all good by me.
Unless SAGA hits multiple platforms on these new gen Amiga's besides the Natami, I don't see it getting much use. If such things are limited to just the newer FPGA Amiga's, there's really a limited market.
Then again, I'm not their target market, as I'm not a gamer and I'd be content with running a "modern" Amiga under barebones lowres low color WB 3.1 anyways.
SAGA is an improvement for a fraction of an already tiny niche market. The number of programmers that will be interested in writing even one line of code that takes advantage of SAGA will probably by counted in dozens, not hundreds or thousands. But, as there are more and more people that return to retro interests, the number of programmers may actually grow over time. When you start with only a handful of programmers that are interested, it is easy to go up from there.
Yeah, software support beyond OCS/ECS/AGA is likely almost nonexistent 
Yes, the there is room for growth as more Amiga users see what can be done with the new features of SAGA.
I doubt we will see much that bangs the hardware in the old fashioned sense, we are probably a decade to late for that to be much of a success. But I do expect SAGA to get a lot of easily converted opensource ports from linux and windows, blender, browsers, various emulators etc.
If these SAGA machines are a decent price, and speed, I could quite happily use one for web browsing and art programs again, and the odd game of quake2 and 3 would not go amiss either.
Having a modern machine, without having bits of hardware hanging off my Amiga would be nice, and if the demo scene gets on board, i'll be even happier.
I have the sneaking suspicion that NatAmi is going to be very expensive though.
Although the Natami will be much more capable than older Classic Amigas, it will still not be competitive with other alternatives for web browsing and picture processing power, so if that is what you are looking for, it will always be a disappointment when compared to modern computers and OSes.
There won't be many people that want to write new code to "bang the hardware" like many 1980's & 1990's programmers did, but there will be some and I do think that this ability is one of the Natami's selling points.
As for price, any small production run, custom computer system is going to be very expensive when compared to something else of similar power that is being manufactured in numbers that are thousands of time higher.