It seems to me the Humble Indie bundles are basically dead at this point and if there is the stray good game it will end up in the overpriced mystery box known as monthly... :-( I predict at some point GOG might try doing bundles since they are already doing the "not/maybe never finished games"
I got the impression that GOG wouldn't be interested in doing bundles or other super-deep-discount offers because the profit margins are very very small, and they also have stated in response to such questions in interviews that they think it's bad for the gaming industry overall. It's possible they're wrong about that and/or that they could change their minds about it of course but my gut tells me they probably wont. Even now if you compare GOG's lowest prices on some games versus the discounts the same games get on Steam or authorized Steam reseller sites, the GOG prices tend to be equal or higher when discounts are applied. This is especially true when you take bundle pricing into account.
This can sometimes make it very difficult to hold out and buy a game here on GOG if one isn't outright opposed to Steam. For example, last year there was a Star Wars bundle on one of the bundle sites (I forget which one) which included 12 Star Wars games for Steam for $12, which works out to $1 per game. For anyone who was holding out waiting for the Star Wars games to come to GOG and then go on sale, most of those games might go on sale here for $2.49-4.99 each likely, and come to well over $30 for all 12. I can't remember if all of the games even existed on GOG yet at the time that bundle was on sale, but I ended up buying the bundle just because it was too good of a deal to pass on. I held the Star Wars game keys in escrow though hoping to still buy them on a good enough sale on GOG over time and then perhaps use the Steam games in trades, giveaways, or gifts. A lot of time passed since then with the Star Wars games going on sales on Steam and its resellers on and off, but they've never really had as deep of discounts on GOG in that same time frame.
As anticipation for the new Star Wars movie built before the new year, I got StarWarsinated and wanted to try some of them out, plus there is always the looming risk if you leave bundle keys and reseller keys sit idle for too long that they might reuse them or be invalid keys for one reason or another so I didn't want to leave them sit any longer. Went ahead and redeemed them all in the end. $12 for 12 games is just too hard of a deal for me to pass up for games like that, although I felt bummed out about it too. I may re-buy some of them on GOG in the future though too perhaps, but probably not the whole lot of them.
If GOG did do bundles or deep discounts like that, they might contribute to game price dilution perhaps, but it'd not likely be any more than what is already happening out there as it is, and would probably cause a lot of us to end up emotionally buying a tonne more games on deep discount than we would for regular discount. :)