Aiki in the broader sense - Yes.
The martial art as generally practiced - No.
The martial art adapted to suit different types - Probably yes.
Is everyone suitable to train/learn might be another way of putting it. Aikido's not broken, its the people that are wrong
Perhaps we should have different aiki practices for people of different abilities/ levels of commitment. To some extent we already don this, e.g. I know of older people, who only practice weapons as they can't take the ukemi any more. Fair enough. Or there is a dojo I know that runs 8 week intro courses to Aikido that are fairly gentle, before students graduate onto their more hardcore regular class, or in most cases leave having had a positive experience, but no real desire to devote large amounts of time and energy to going further.
If we can practice in different ways on the mat (e.g.to suit kids, smaller people, more aggressive people, etc) then Aikido classes should be suitable for almost everyone (not ugly people obviously - joke). Good instructors understand the principles of Aikido which can be applied to various forms of body/mind. Aiki is after all about blneding and adpting.
Just my 2 pence,