You can disagree all you want, it doesn't change the fact Soviet subs were not designed to operate past a 20 year service life.
Even if I were to accept that were true, the Soviets were facing different problems than the Russians are now.
Buying small compact efficient electronics for foreign sources was not an option. Compact vertical launch systems that mean a smaller sub can perform a different set of functions each time she sails. Multipurpose subs can finally be created that have the performance of a customised sub in each role she takes on.
Future Russian subs will be smaller yet have flexibility in the weapons carried and missions they can perform.
Soviet subs already had better automation and were faster and deeper diving than western subs, there is no reason why future Russian subs... even mini subs cannot take that automation further to allow much longer deployments on a much wider range of missions than ever before.
They have pressurised hulls with many more tolerance requirements than
any surface ship and since they have all their systems crammed into
compartments, it is much more expensive to upgrade them as the hull has
to be compromised to do it.
I am not suggesting the entire fleet stays in service forever. Small changes to improve commonality of systems/sensors/weapons/propulsion/etc etc might be made or might not. The point is that with regular overhauls and upgrades they will last a lot better than they have over the past 20 years without proper maintainence and upgrades.
Russia said it will not pay a dime for the rusted out Vilna Ukraina.
Yet they have said they will accept it for free... why would they want such garbage?
Perhaps with a 4th Slava class and upgrade of all three vessels makes more sense?
An upgrade of in service vessels is more likely than scratch building replacements of similar size.
As you mentioned, the Admiral K is going to be docked until 2017 so
there is not going to be a carrier to defend for the next 6 years and
new carriers will not be built until after 2020. It puts the need for
more AAW ships on the back-burner.
Problem is that things like the Georgian invasion of South Ossetia often occur without warning, so you have to use the tools you have available. Right now you have some fairly obsolete large ships still in service... you can scrap them and save a little money, or you can spend money now to upgrade them so they will remain useful for a while longer. If you scrap them you create a gap that you will not be able to fill for quite some time... you wont be able to afford to buy big support ships AND carriers, so if you let the current big ships rust into the scrapyard by the time you get to 2020 and are considering starting with new carriers there wont be any vessels to operate with them, so you will need to decide which to make first.... carriers, or the big support ships carriers need to operate with. Now big ships are useful on their own and they make carrier groups possible so having them now is not a big waste of cash... especially if their upgrade spends money on Russian companies that make propulsion systems for ships and radar systems and sonar systems and missiles and guns etc etc. If you just start making small ships... guess what... the people who make big ships will find another job, and Russia will have to crawl to France to buy a carrier design from them... and some big ship designs too because Russian shipyards can't handle that.
If instead, the current large ships get unified upgrades that use all the new components they want to use in their new build ships then some of the teething problems with these systems can be worked out and production volumes should reduce prices... and get Russians working.
Most of Russia's vital interests can be protected from land based assets so a blue water navy is really a luxury right now.
If you want to be a global power, then you need a global reach. Britain didn't become a world power and then decided it could afford to spend a bit of this extra cash on a decent navy. The navy allowed Britain to become a global power and a tiny otherwise fairly unremarkable country had an empire that spanned the globe.
To be honest there is no reason why these 40-50 nuke propelled subs need to be large heavy expensive vessels.
With two major fleets that is 20-25 per northern and pacific fleet... with SSBNs being maybe 15 of those in one fleet or 6-8 in each and the rest a variety of SSGNs and smaller subs such a target is perfectly possible if you create a new class of sub that is a smaller cheaper sub the size of a conventional vessel with a nuclear propulsion system with vertical launch tubes for all sorts of missiles and a modest torpedo load... sort of like an Alpha class but without the high speed and expensive liquid metal reactor.
Sort of a coastal SSN with standard multipurpose weapons, decent but not amazing speed, good sonar, and a relatively small crew so that manning is not a problem.