Especially since it seems this is almost certainly connected to the actual comment I quoted from Grand Duke Nikolai, it seems likely this is what they had in mind. So not independence as a satellite, but a certain level of devolution within the Empire. That seems much less likely to win over Poles for the long-term, but nevertheless informs me as to whether to go along with Russian plans for incorporating Austrian Galicia (not just the Eastern half of Lodomeria surrounding Lemberg).
Well, there was opposition even in Russian government calling for higher level of autonomy for Poland. Grand Duke Nikolai, Sazonov, Krivoshein to name the few of them. But the emperor didn't favor their plans.
I don't think Poles would raise against Russian Empire after WWI. After all, both previous Polish uprisings failed. Mobilization into Russian army in 1914 was extremely successful in Poland. Russian military authorities feared that there would be massive draft evasion and desertion among ethinc Poles, but this didn't happen: draft was very successful and there was a lot of Polish volunteers who drafted voluntarily into the ranks of Russian army.
I do, but they are in Russian only. There is good article by S.V. Lyubichankovsky about Stürmer's proposal in 'Otechestvennyiye Archivy' ("Исторические Архивы") historical magazine No. 1, 2009. Not only he gives historiography of the question, but also gives full text of Stürmer's memorandum of July 7, 1916 to Nicholas II about the very idea of reform.
I wonder for example whether the views of Sturmer or Sazonov would have predominated during the days where Sazonov is still in power, before he gets dismissed. Perhaps the Russian gov itself was not yet sure of a decision, hence the vagueness in their public statement.
Russian imperial government was split into two 'parties':
the dualists (supporters of status quo and
executive monarchy where the government is responsible before the Czar and the Czar appoints all the ministers while the Duma is only a legislative body) and the
parliamentarists (supporters of parliamentary monarchy where the government would be responsible before the Duma and the Duma would appoint Prime Minister who would then choose members of his cabinet from members of Duma). Funny thing is that there've been no
reactionaries (supporters of absolute monarchy) in the government at all. Nicholas II selected members of government carefully, trying always to keep balance between two parties. But Prime Ministers almost always were dualists. If you tell me what exact time period you are interested in, I can name you all dualists and parliamentarists in the government. Broad autonomy for Poland would be supported by parliamentarists while dualists would prefer something less ambitious.