Since the stealthy guilds won't be in at launch will there be a respec option?

Normally I'm not in favour of respeccing, but in this case it feels like I'm going to have to make a throwaway character until I can join the Brotherhood and the Thieves Guild. Or am I misunderstanding the nature between guild skill trees and levelling?

As far as I understand the guilds are not mutually exclusive. You can join both mage's and fighter's guild on one character. So you'd probably also be able to join the thieves' guild as well, when they come into the game.

On top of that there will definitely be a respecc option.

I thought that the stealthy guilds would be available at launch - but they werent available currently.

Well, there isn't any really any need to respec in this regard. ZOS have stated they plan to making progression through the skill trees partially separate from leveling - that is leveling isn't the only way to get perk points. When the Thieves' guild and The Dark Brotherhood do eventually make their way into the game (or if it will now be in there at launch, ZOS have said the release date has been pushed back to give a more fuller Elder Scrolls experience) you can just begin a stealth approach to playing straight away as a novice and work your way up back to the level you are at with your skills you were using before.

They did state that there will be a level of control of backpedaling your perk selection in some regard, but I'm not exactly sure if that will be really needed. Sure, if you selected a perk that you later decided you don't want, yes, I can see that being a little bit of a problem. but it's not the end of the world for how you want to play your character, instead it'll only take you a little more effort and time to progress but either leveling up again and/or gathering three skyshards for the additional perk point.