June 2014 will be the last month PSP units are shipped to Japan. The platform launched on December 12, 2004.

Sony will offer discounts towards PS Vita products if you trade in your PSP. Additionally, the company will launch the PS Vita Super Value Pack in Japan.

http://dengekionline.com/elem/000/000/861/861723/

Will we see a sharp increase in sales or a marginal boost?

Worked for Nintendo and ceasing Wii shipments so Wii U could sell.

in my opinion , i do not think it will have a major boost as a matter of fact i think the case would be more on the very slight increase or really that much of a boost AT ALL!

In my Opinion Sony is expecting more of a tough climb for PSVita and that they will continue to support PSVita as a platform so long as the chain stores keep restocking the PSVita in one shape or form. I doubt Sony is in very much of a hurry to put more Money into a Mobile playstation other than smart devices from here on out and that would be a standard design smartphone that if you want physical controls a bluetooth game pad will be the Answer for that request. from my view A dedicated mobile playstation will move from a current dedicated built handheld game platform to more of a agnostic smartphone and tablet "App store" market design dynamic for a mobile game handheld for Sony. concede the dedicated handheld game console market to Nintendo, because they can compete indirectly instead of directly and still compete. they are selling over 9+ million smartphones a sales Quarter moving playstation over to smartphones i think is Kaz and the board of directors direction. Hey it works for Apple, Google and Microsoft App stores are the future for anyone other than Nintendo in dedicated handheld console market.

the % of market share in advantage for Nintendo is too great vs the only other handheld to come anywhere near that much of a market share in the dedicated game handheld space is Sony which currently is 2nd place, but that 2nd place standing is so far away from Nintendo's 1st place it's pretty much a Nintendo Monopoly. So Sony moving to Smartphones is more growth % for an increase in market share for the software sales than in dedicated handhelds.

After the PSP, The PSPGo, the Xperia Play, and now the PSVita i doubt very much Sony has the stomach to further persue moving forward on pretty much a money sink for this part of the market at least with smartphones Sony is or at least stands a chance to make a "playstation esk App store" for smartphones and tablets that can generate more cash flow for Sony at this point. just keeping it real people.

One of my biggest pet peeves.
off topic, the word you're looking for is affect, not effect.
use effect as a noun. Affect is the common verb

I hear you. I don't have much effection for people who get that wrong.

PSP has been selling like 1.5k/week in Japan. The time to migrate the audience by discontinuing it is long gone. Will have a negligible affect on hardware sales. Not all games are on PSN, either.

(That one was just for you, Prof!)

No immediate effect, but hopefully this'll stop cross-gen or PSP exclusives from still being announced.

Nothing. PSP sales are already low. PS3 to PS4 on the other hand could help a lot.

Obviously positive, but without a price cut it will give a negligible boost after the PSP trade in offer will expire.
Coupled with a price cut, instead, it could really give a significant boost.

Won't do shit until Sony makes a System Seller for the vita