Ok so I know it would be a big job, but i think it would be very profitable for Bethesda, and i think the players would love it. I know my wife and I would..
Anyway, my idea is to port oblivion into skyrim as it is, leave everything as it is, quests, guilds, the land, everything. Make upgrades to the graphics, and where needed in the scripts. I understand this would be a huge job, but all the quests are already made, the majority of voice acting will mostly be there, maybe add some new ones for immersion. The layout of the dungeons and land are already there, so just make upgrades where needed, and add everything that is needed for smithing as well as other professions if need be..
I know there would be a lot of things I haven't mentioned that would need to be done, that I do not know about, that would cause problems, but am confident Bethesda would be more than capable of handling it.
As for the story, you would start in oblivion, and complete the storyline there until the main quest is complete. At this point there are 3 ways i can think of to merge it into Skyrim's start.

1) you receive a message from somebody that has been studying the elder scrolls, and has happened upon an entry that foretells of a hero that will be needed in skyrim in the future, and after all your heroic deeds, he thinks that you are the hero the scrolls are talking about. After some investigations he locates someone who has the aptitude to send you there with an elder scroll, that he thinks he has located, so he gets you to retrieve it, and sends you there, where you are captured by imperials with the storm clocks trying to cross the border.. OR

2) After the main quest line, you get news of trouble in skyrim, and as you approach the border, you are attacked and die, where the new character for skyrim, comes across your remains and picks up your gear and a journal containing your deeds back in Oblivion. He then is captured by the imperials where the skyrim storyline will commence. (personally i dont think this one will work, but you never know, bethesda could use it for a better idea. OR

3) through the play through of oblivion, you marry and have a child. At the end of the main quest line, you get a quest to settle down, and when you do this quest skyrim will start, and the character you are playing, will be your last descendent. The character can have a special tree that reflects the character from oblivion, that gives permanent buffs/powers that have been inherited through the family genes. The character in oblivion would have been dragon born, but did not know it, which would explain why he had the strength to deal with the oblivion crisis, and this strength was passed down the blood line to the character in skyrim.

Anyway thats it, please dont troll me, this is just my idea and i hope bethesda likes it. I honestly think this could work to benefit both Bethesda and the playerbase.Make some money for Bethesda and give the players a realy good game experiance for both new and veteren players.

Never happen.

For a start it isn't that easy to just 'port' over one game into another. First, the engine is different enough that you'd have massive problems just doing the port. Ids for everything in the game would need changing to reflect differences.

It would be easier to rebuild things from scratch, which they won't. They've done with Oblivion and don't have the resources and manpower to shift away from their current projects to basically redo Oblivion.

You are entitled to your opinion, of course, but there is a reason why game remakes are nonexistent. Too much trouble for so little gain to remake a game that you already have made. And since this would be a direct copy of Oblivion on the new engine, sales would be low because of the fact that a lot of people wouldn't be buying it simply because they already have played Oblivion to death.

A new game needs a new setting and a new plot. Recycling old games is pointless and that shows in the pretty much nonexistent amount of game remakes.