M-46 is 55 caliber length for its 130mm bore and Giatsint has 54 caliber length for its 152mm bore with both matching other range wise.
M-46 is good howitzer for its caliber and maybe new 130mm should be considered for truck based howitzers instead of heavier 152mm.
Though 122mm howitzer could be made to match range of M-46 with long enough barrel thus not easy to come up with an ideal solution.
Though it would be better to have 130mm howitzer and retire 122mm since there is also 122mm rockets thus avoid potential confusion.
If someone just states that there is need for 122mm ammunition without clarification and what not. Its possible to happen.
Thing is, 122mm D-30 howitzer is on its own, iconic and legendary classic of a howitzer. It's simple, reliable, robust, accurate and easy to use and move around. It's often referred to as the AK-47 of howitzers, and commands a good price in the arms market. There are too many of them made and too much stock of its ammunition left, the supply will last for a long time. It can be used as a direct fire weapon with great accuracy.
For this reason D-30 howitzer has become bread and butter artillery for both sides of the conflict.
You can't get rid of it that easily.
Another thing to remember is that D-30 can fire Kitolov-2M guided ammunition which is effectively a Krasnopol in 122mm shell. This is already used heavily in the war. The M-46 lacks a guided shell.
Maybe they could use the 130mm for truck artillery but it's pointless now that you have the 2A79 and the 2A80 used on the Malva. To put it in perspective, the 2A64 is whats used on the MSTA-S and equivalent to the MSTA-B which there are also plenty in stock, and might still be being made. This cannon has similar stats to the Giatsint and the M-46, with 27km general projectile and 40km with active reactive. With Krasnopol, it reaches 43km+.
The 2A79 belongs to the MSTA-SM2, which is the current MSTA-S in production and which older models are being upgraded to. The general projectile range is now over 30km, and 40km+ with active reactive. Krasnopol will reach even further. I would assume this is the current gun of the 2S43 Malva until the 2A88 from the Koalitsya comes along. This pushes the general projectile range pass 40km and active reactive to maybe 60 with Krasnopol up to 80km.
So M-46 is already superceded at this point, and will be used since there's still a supply of old M-46 along with the DPRK shell supply. There's some people are saying that the Russians should just adopt 155mm as it will also allow you to partake use of DPRK and Iran 155mm ammunition.