Not in the main western countries, not sure what's happening in Greece and Turkey they may still have some 203mm. Israel used to be a significant user of 175mm but may have upgunned to 203mm. No doubt there are still some 180mm lurking around in the Middle East. Presumably Russia and/or otehr successor states to the USSR may still have some 203mm and 240mm, in stock if not in units. China also has 203mm. Not sure what heavy guns are being used in India's artillery division(s)

Russia has about 130 2S7 Pion SP gun (30 in service) plus about 400 240-mm 2S4 SP mortars plus 700 200-mm MRL Uragan and about 100 300-mm MRL "Smerch". And unknown number 300-mm short range MRL TOS1 (Buratino)

I think he means cannons and mortars not MRL. Israel got rid of all of its 175/203mm cannons some years ago. I think you can only see large caliber art. in eastern armies this days. In the west, the biggest guns are 155mm 52 caliber cannon. If you wnt a bigger punch you use MLRS or airpower.

A firm in South Africa used to offer a mobile 203mm on a huge 4x4 chassis.

in some point man has to pick up and carry separate round and propelant. smart heads made a desision go no larger than 152/155mm, rest is getting phased out.Average round is about 35-45 kilogram, and that is a lot. working and liquid proppelants, roket busters, self guidings, longer tubes up to57 caliber, gps, clusters, etc, more effective, more expensive. If you can afford use artillery instead of ifantry, also attack helicopters, airplanes are future mobile artillery as well

Aircraft and attk heli have very different characteristcs to arty, particulalry in terms of availability. Furthermore there is no rush to ditch 'dumb' shells because the are the best solution to some situations. However, the role of heavy guns or mortars against hard 'point' targets is clearly best left to something smart.

M110 uses a 203mm round. I think Taiwan still has some. 203mm is of course being phased out. That's why US uses the spare 8" barrels for something else - deep penetrating bombs. Still, with accuracy being more important than diameter, smaller diameter makes sense.

8 inch (203mm) are long gone and been replaced by MLRS.

What often determines an artillery piece service life is the stock of ammunition - shells are far more expensive than the guns. (That is probably why we in Denmark kept big German naval guns in service as coastal artillery untill 4 or 5 years ago. If you have to consider a new production run of shells, they will bought at todays prices, so they tend to be on the costlier side. If on the other hand you get a rocket at a comparatively cheap price, why not dispense with the big tube that takes a lot of people to handle and the lot of people bring the shells forward????

Artillery life is dependent on usage. The various components have a life measured in EFC's, Effective Full Charge's. The M776 cannon has a specified EFC life of 1500 EFC's before it should reach condemenation criteria as determined by pullover measurement. The recoil system has an EFC life of 4500 EFC's before total rebuild is required. The rest of the weapon structure should last as long as required providing the weapon is PMCS'd correctly.