Obviously this update would be for f2p and p2p. There should be more maps for clan wars. Also capture the flag for a game mode. Also a teleport spell to clan wars. Also more game modes that they come up with. Just think about it, it would be an awsome update.

There's already a wide arrangement of maps and the game's necklace teleports you to clanwars.

Plus, capture the flag: Runescape Edition sounds like it'd be easy to win. Protection prayer on and a few energy pots.

Capture the flag? Maybe... but it would be like something noobish with no use at all. Also you have castle wars for that.
More maps? Maybe... it would be cooler with more maps but i think that there will be less games... Because you have 50% chances that players like the maps and 50% that they dont. So some players dont want to fight because they dont like the map. (Happens to me in a woods map).
About the teleport spell, there is a games necklace that you need to rub it and it teleports to clan wars. You need to be member.

I want an arena that is raining, and has lightning strikes on the ground. Unlucky fighters struck by lighting will take damage accordingly to their equipment.

This would be nice, but I know it will never come-
I want "Clan Armor" in which the clan leader can customize his clan's armor appearances, (must pay lotza GP for the most awesome things, eg- 1mil for Prestigious Spiked Left Spaulder). In order to obtain clan armor, a player must trade in their regular armor to an NPC to receive a prismatic equivalent to the armor.

Loyal friends and officers will be able to wear specific customized armors made by the clan leader. Lower recruits or free loaders will be given armors that don't have as striking as a look, but either way customized by the leader themselves.

Customizations include: Helmet and Add Ons; Left and Right Pauldrons, Arms, and Chest; Greaves, Tassets and Cuisses; Cape; and Symbols.

Capture the flag sounds like a great idea for ftp castle wars.

Castle Wars IS capture the flag.