I had a couple of odd ideas that might be worth considering for implementation. Will admit upfront -- I'm relatively new to the game -- despite investing a few years into it..

Secret shop -- obviously, it's removal is a surprise to the majority of us. Personally I don't think there was anything particularly wrong with the shop, though, I too found it cumbersome to wield multiple units to 'get' items. I would end up simply walking there myself. With that said, removing it probably wasn't a fantastic idea -- at least not with a valid replacement.

My thoughts: A roaming shopkeeper (or teleporting one) as a replacement.
One game I used to play back in the day had a particular keeper whom would teleport around at random intervals and sell odd items, I think allocating some special items to said shopkeepr would be nice. The keen part of this particular shopkeeper is that when anyone attacked him he would disappear, wait a bit and then teleport somewhere else.

Some special items for the guy
Special items that might be cool to throw on him would be someone elses best guess, but combination wards (e.g. the wards in one) would be spiffy. Other items that could be handy would be one-use mirrors that you could use to 'unfog' a part of the map temporarily without going there, obviously more expensive than wards themselves. You could really do endless amounts of things with a character like this that bounces around, including 'persistent' items that you keep after a game is over (think -- special symbols, name colors, etc.) that only load one in a billion times off said roaming shopkeeper.

Traps! I think something sincerely lacking are traps, and obviously while a great deal of the skills / spells in the game are character specific, it would be nice to have usable items (traps, pits, etc.) that one could setup to use anywhere on the map. They'd add another interesting dynamic.

As for the secret shop..
I think it would have been special to only have a single secret shop between the two teams where ganking would increase significantly, vs. having a shop per team. Obviously this is a slight bit more difficult considering the map's constraints but it could be thought out thoroughly and implemented in future maps.