During this Summer sale, can I expect any games on sale that are NOT presently in bundles to STAY on sale until the end of the Summer sale?

Well considering they didn't say anything, then yes, it looks like that's going to be the case.

Yep, but with some exceptions:
http://www.gog.com/forum/general/2013_nodrm_summer_sale_begins_on_gogcom/post129

Can you elaborate? I'd like to understand your reasoning before marking a solution :D Can I take this to mean the games (and publishers/devs) specified will include the ONLY games that won't stay on sale the whole time?

Well, those publishers (just like what happened on Christmas) will only be discounted for the 1st week... I bet they'll be on a bundle before that..

My understanding is that all currently discounted games, except for those from the specified publishers, will be on sale throughout the entire Summer Sale.

That said, GOG is usually pretty good about giving a heads-up before discounts end, so if anything changes you should get a day or two's notice anyway.

Looks like we are not allowed to gift the Bundles either - unless I am missing something.

its got the 'gift entire pack' button on the promo page. near the bottom left side.
http://www.gog.com/promo/definitive_dungeons_and_dragons

and you can add individual titles to your cart and get the 80% off if you have all the titles and gift the individual code (for the D&D which i have)

http://www.gog.com/promo/wide_awake_bundle
has the 'gift entire pack' button as well.

Nuts - I must have been tired last night - I missed that completely - usually in the upper right under the you own them all area - instead of gift them it just said conratz you own them all

Does this mean that there's no chance that any of theses publishers games will end up as a daily-deal?

I'm not sure whether to buy the few titles from these publishers I have wishlisted this week... or hold out (and risk losing their sale altogether) waiting for a daily-steal?

Well... I can't be sure, but I think they MIGHT be in a bundle, either before they go off sale individually, or after, more probably the former. My advice would be to prioritize - buy those that are top of your wishlist before the first week of the summer sale goes away, and if they put them in bundle after that, buy the rest then.

Solid advice, thank you!

If you want to buy lots of games you don't know about, say which they are, and maybe me or someone else can tell you what to get first :)