You are on to something. The one thing that is clearly emerging from this latest attack is that Al Shabaab has now been incorporated in Kenya. It is now a domestic terror organization that would no longer need to cross the border. Once can see the ferocity of the attack and the improved tactics.
According to Al Shabaab quoted on BBC, they entered the college early without the guards knowing about it. They then proceeded to kill as many as they could. My take is that they then dressed up as students and fled the site, leaving behind a squad of hardened suicide bombers - probably from Somalia, to fend off the security forces while the other party escaped. Since they travel with their own "journalists", I assume they need time to allow these support corps to reached safety.
If they are in Kenya, then expect more attacks.
Your suggestion that the Coast is vulnerable is spot on. The last video had people whose mother tongue Swahili was pure Kimvita.
The security forces are not helping either. They have launched reprisals at the Coast, NEP and parts of Nairobi. These draconian measures push Muslims and Somalis in to the welcoming arms of Al Shabaab. The raping of women in Garissa when KDF burnt a market may have served to plant Al Shabaab in that town.
It doesn't. And that was one of main risk for us going into Somalia..while NEP remained embittered and marginalized for generations. If we needed a buffer with Somalia..we had one..in NEP.
Can AMISON or KDF really defeat Alshabab..mm outside the main towns and ports..the answer is an obvious NO.
We are looking at 20yrs plus of low key guerrilla style attacks from Alshaabab and their kenyan sympathisers mostly in NEP and Coast.