Direct quote
" The trustee may distribute as much of the net income and/or principal of the trust estate as the Trustee deems necessary or desirable in his absolute discretion for Katherine's care, support, maintenance, comfort and well-being. Distributions shall be made first from the net income of the trust estate and if net income is insufficient from the principal of the trust estate"
Meaning : 40% of the Estate is put into a separate account named as "Katherine Jackson Trust". Preferably net income from this 40% is used to provide for Katherine's care, support, maintenance, comfort and well-being during her lifetime. The amount is to be determined by the executors.
As you can see from "sufficient / insufficient" she will not be given 40% upfront and she'll only get an amount necessary or desirable for her care.
Direct quote
"Upon Katherine's death the remaining balance of the trust estate of Katherine Jackson Trust shall be added to the Michael Jackson Children's Trust".
Meaning: When she dies the account established for her is closed and the remaining assets (40%) put into is transfered into MJ's kids accounts.
so you can see the 40% is put aside to be used for Katherine's care. Also as you can see the income is to be used first meaning that the principal is protected. She never gets a lump sum or control of any of the assets and everything eventually goes to MJ's kids. However I'm sure that once the probate is over the money given to her (allowance) could and will be increased. ( as estate still has debts judge determined the allowance on a "need basis", once the debts are paid of executors can pay as much as they want and do not need to limit it to "need" basis).