What will be of the "Less" classes?

Well, let's do the calculation, shall we?

Let's figure that a Dexless sin will be using a 51 ATK Kandayo (+18 ATK from base), 10 ATK WG, 12 ATK pot, and Ilbies - a very likely scenario. This gives you 100 ATK.
To keep things the same, let's assume a Red Craven with the same boost to weapon attack that the Kandayo got (+18) bringing the total attack to 65 ATK, 10 ATK WG, 12 ATK pot, and Ilbies. This brings the total to 114.

Dexless Sin:
2.00 * (4 * (500 + 50) + 25) * (100 / 100) = 4450
All sins must have 25 base DEX, so that's why 25 is there.

Regular Dex:
You said the regular dex sin would have 100 DEX, which is really +75 off of the base 25. So I will take 75 from LUK and put that into DEX for a total of 425 LUK and 100 DEX
2.00 * (4 * (425 + 42) + 100) * (114 / 100) = 4487

Dex sins have just as good damage as dexless sins. Perhaps even better, though, because higher level items grant better potential system bonuses. So, in the end, DEX sins make a hell of a lot more sense than dexless.

For example, level 100 items which the DEX sin can wear can give +9% +9% +9% on LUK which gives +27%. The Kandayo can only give +6% +6% +6% = 18%. Which would you rather have?

wtp? Kandayo?? i loled...

Where you at man? dexless sins (the dexless claw users anyways) nowadays use Skanda which is usually 60ish atk if well scrolled and even better the level 77 maple claw in KMS

Plus you didn't account for those godly dexless lampion/Sleeve/Craven using NLs that can equip the highest level claws without investing any points in dex...which most NL will EVENTUALLY reach at some point and it will be a hassel and a huge waste of money to reset those stats back from dex

So inconclusion dexless sins will always win both in the long run and short run and way easier to fund, I believe it is the same for other statless classes also but I'm too lazy to do the calculations