I see no reason why the cult of the offensive would lapse. The 'Law of the Cadres' would mean that by 1917 the French Army would be longer serving than the Germans (3 year conscription) so better trained...assuming the French Left didn't get it overturned (they were politically gearing up to get the 1913 law repealed in 1914). I could see French uniforms changing by 1917, but AFAIK as of 1914 there wasn't significant pressure to make that happen yet. I don't see major changes to the French army happening beyond a better artillery park, but one still much worse than the Germans (the above 105mm howitzer was meant to be a
corps/
army level support gun rather than a division level one for the Germans). IOTL they only adopted modern 155mm howitzers after failed attacks in the Artois in 1915; they thought their existing 1904 155s were good enough until then and rejected 1913 designed modern versions until their infantry got slaughtered in trench warfare.
I could also see more MGs and perhaps LMGs being a thing for the French army by 1917. The Chauchat existed by 1914:
https://en.wikipedia.org/wiki/Chauchat
By July 1914, the Blue Horizon uniform had been officially accepted by the Parliament and like OTL, would have begun to equip French units in early-mid 1915 (though likely not a the frantic pace of OTL).
The Chauchat was indeed already a very advanced prototype (and far more refined than OTL but still cheaper than any other design like Madsen or Lewis LMGs), it would have probably been adopted as a more reliable and less rushed weapon than OTL but again, likely not mass produced as OTL (but still more produced than a Lewis or a Benet-Mercier).
105mm and 155mm Hotwitzers would be introduced at a corps level like you said and would likely replace the 48 75 mm guns serving as Corps artillery. Those heavy guns would probably be intended for counter-battery fire. Joffre and Dubail had supported this since 1911 and it was intended to be become a reality in 1914.
Likely no helmets since it was the massive casualties of the first weeks (and the reports of field hospitals following the fights) which accelerated the adoption of helmets.
The Saint-Etienne would be gradually replaced by the Hotchkiss (already an idea accepted by the French Army and already used by the French Legion and some colonial units), easier to produce.
The Meunier rifle could become a limited reality since it was intended to be a sharpshooter rifle at the beginning (ten per company) before being more widely issued (to what extant I do not know): it was the first real and reliable semi-auto rifle with an excellent cartridge (very similar to the 7,92mm Mauser so I guess it means something).
The Navy would really begin to have more modern ships, including 10 excellent light cruisers (Gravière class) and modern destroyers comparable to the British and German ones and very capable submarines. Dreadnought would be modern but hampered by the limited elevation of their main guns (notably for the Courbet and Bretagne class, the issue would be fixed for the Normandie class).
1917 would also mean better Russian and more prepared Belgian Armies btw. To the point Germany would perhaps abandon the schlieffen plan and concentrate its initial blows against Russia. About improvement of the German Army I do not know but I imagine there would be. One thing though: the German Army wasn't very enthusiast about LMGs initially in WW1 to the point they massively used captured Lewis guns (up to 10 000 according to CRArsenal) and their lightened Maxim gun wasn't really great for this purpose.
On a side note, A-H would probably have its mauser-action service rifle adopted.
