There seems to be most everything you might need in the guild halls now. However as far as I know if you are a pve character you have two options when it comes to switching your secondary profession. One is to go to the profession changer in Senji's Corner. Two is to complete 1 of various quest in the Crystal Desert so that you can talk to a ghost for a switch.
No matter which way you choose if you wish to use your pve characters for pvp (which I like to do so that my exp is not wasted on a pvp character) you are faced with a hassle everytime you need to change your 2nd. You have to leave your party in Heroes Ascent/Guild Hall/Team Arena and go out traveling by boat to Tyria/Cantha then journey to a certain town which will allow to switch by talking to a NPC.
Awhile back I asked that this be added like the rune traders and such where to Heroes Ascent. Then when I heard about NPCs in the guild hall I assumed that a profession changer HAD to be one of them. However I was wrong this profession changer was added to Senji's corner instead? I say WTF!?!?!?!?!?
EDIT by King Symeon:
See post 46 of this thread for summaries of each of the ideas for profession changing and a poll for each.
L

Thanks for explaining your idea in more detail.