Bare in mind, the MMRT will not be completed until 2026, there is a slim chance any of your listed items will be touched before then. That said, here's what I suggest you could expect with each of your listed item:
Melbourne Airport line
Not before 2026, via Sunshine is currently the preffered route owing to its ability to then connect with many regional lines. It would require its own tracks from Sunshine to the CBD. It's important to note that Melbourne Airport themselves are saying that they will require it by 2035, so they may indeed be asked to helo fund it, therefore, 2026 is probably the best outcome you can expect here, 2035 is more likely, but still optimistic.
Epping North line
Medium term, ie:- not until after 2037 (at least 20 years away), not likely to be built before Metro 2
Doncaster line
Highly unlikely to happen any time soon as a full heavy rail line, light rail may be possible sooner, otherwise perhaps after Metro 2, if that ever even happens
Rowville line
Unlikeley to happen as Heavy Rail. Light rail a better chance, still not likely to happen inside the next 15 years. Was looked into by the Bailliue govt, put in the too hard/ too expensive basket.
Clifton Hill-Newport underground line
The best case scenario is that early planning, soil testing, detailed planning and any required property acquisition is completed and funding is secured from both the private sector and the commonwealth in time for construction to start in 2026, immediately following the completion of MMRT (Metro 1). Then, it will likely take at least 12 years to build the thing. Again, I said that was the best possible outcome, knowing the way government and its beuracracies work, I wouldn't hold onto any hope that it will be done with such expediency. In summary, not likely to be finished before 2040.
Melton electrification
Everything right now is pointing for this to happen by day 1 of MMRT being operational, so 2026. Not a given though.
Wyndham Vale electrification
Could theoretically be done tomorrow, isn't though. Best case scenario has it happening in the next 9-10 years, same timeline as Melton.
Wallan electrification
Not seen as urgent as Melton, Wyndham Vale, Melbourne Airport or some of the smaller projects, although with the amount of development happening around that corridor, expect it to be a pressing matter within 10-15 years. Construction to be complete within 10 - 20 years.
Clyde electrification (should read extension)
Likeley to be the next big step for the outer South East. Along with full duplication of the Cranbourne line. won't happen before Dandenong line upgrade is finished, and the new HCMTs are put into service. Best case scenario is 10-15 years
Baxter electrification
A bit harder to judge this one. The main push for this project is from an operational requirement rather than a passenger demand, so theoretically could happen much sooner than many others on this list, or then again, may not happen at all.
Sunshine-Deer Park quadruplication
Would be done as part of the Melton electrification project. Would also likely include removal of level crossings at Fitzgerald Rd, Station St and Robinsons Rd. Also rebuild of the very spartan Ardeer station.
Mooroolbark-Lilydale duplication
Not urgent, not a growth corridor.
Ferntree Gully-Belgrave duplication
Not urgent, at best Ferntree Gully to Upper Ferntree Gully may see duplication inside the next 30 years, the rest is unlikely. Not a growth corridor
Cranbourne line duplication (possibly same time as Clyde electrification)
See above (Clyde extension)
Hurstbridge line duplication (remainder)
Heidelberg - Rosanna is underway now, Greensborough - Eltham is being planned, likely to be complete within the next 10 years, beyond that, not urgent, mostly rural land, not a growth corridor.
Gowrie-Upfield duplication (and Somerton link)
Likely to be done with any extension of electrification to Wallan, so best outcome sees it happening in maybe 10 - 15 years
Altona Loop duplication (remainder)
Not urgent, despite what the locals think. Improvements can be made in the short term though, duplicate sections, not necisserily going to see the lot done for quite some time though.
Caulfield - Dandenong quadding
Whilst this was not on your list, I beleive this will need to be done long before many of the things on this list. 2 express tracks and 2 local tracks (only the latter with platforms) will be needed before too long, not palletable right now with the anti- skyrail protests still carrying some weight. May be worth visiting though in say 10 years time.
This, I feel is the minimum of what should happen to the Melbourne network in the next 10-15 years. If there are any other suggestions to what people should think be implemented, then feel free to put forward suggestions.
Yeah, see when you make statements like this you need to remind yourself that the state is not run by railfans. It has a limited supply of funds, to build all of what you have listed within the next 15 years would require massive funding cuts to important sectors like Health, Education, Policing and Corrections, and the Environment.
The reality is, even though I have listed many of the above as 10 - 15 years, I have also said that would be the best outcome. Don't hold on to any expectation that all of that will happen. If I could say one thing was certain, it would be that all of what you have listed won't be built within 20 years, that you can take to the bank.
I'm not saying there isn't merit in every single item listed, just that reality gets in the way sometimes.
how about electrify stoney point that is suburban too!!
Everything has to wait for its turn to come around, the Stony Point line is behind everything else on this list, and some others that are yet to be mentioned.
Stony Point currently gets 10 trains a day, those trains are 1 or 2 car Sprinters. Electrifying that would be unjustifiable.